Parabolic transformation cloaks for unbounded and bounded cloaking of matter waves

Science.gov (United States)

Chang, Yu-Hsuan; Lin, De-Hone

2014-01-01

Parabolic quantum cloaks with unbounded and bounded invisible regions are presented with the method of transformation design. The mass parameters of particles for perfect cloaking are shown to be constant along the parabolic coordinate axes of the cloaking shells. The invisibility performance of the cloaks is inspected from the viewpoints of waves and probability currents. The latter shows the controllable characteristic of a probability current by a quantum cloak. It also provides us with a simpler and more efficient way of exhibiting the performance of a quantum cloak without the solutions of the transformed wave equation. Through quantitative analysis of streamline structures in the cloaking shell, one defines the efficiency of the presented quantum cloak in the situation of oblique incidence. The cloaking models presented here give us more choices for testing and applying quantum cloaking.

Acoustic cloak/anti-cloak device with realizable passive/active metamaterials

International Nuclear Information System (INIS)

Shen Huijie; Wen Jihong; Yu Dianlong; Cai Li; Wen Xisen; Païdoussis, Michael P.

2012-01-01

Utilizing the coordinate transformation method, together with exchange of variables between Maxwell's equations and the acoustic equations with axial-invariance in cylindrical coordinates, the acoustic parameters (anisotropic density and scalar bulk modulus) for an ideal cloak and an ideal anti-cloak are obtained. An anti-cloak allows the inside object to ‘see’ outside, but to be invisible from outside; whereas a cloak is invisible from outside, but ‘blind’ from inside. Utilizing a scattering algorithm developed in this paper, the pressure field calculation of the cloak/anti-cloak is performed and the concepts and characteristics of the acoustic cloak/anti-cloak are revisited. To be more easily achievable experimentally, a multilayered cloak/anti-cloak model with homogeneous isotropic materials is introduced, and its corresponding pressure distributions are calculated. Also, the total scattering cross-section curves for the multilayered cloak and anti-cloak over a certain frequency range are presented and compared. Finally, an active acoustic metamaterial made up of piezo-diaphragm cavity arrays is designed for the cloak/anti-cloak. Taking into account the coupling between adjacent cavity cells, a multi-control strategy for piezo-diaphragm cavity arrays is exploited, rendering possible wide ranges of effective densities and effective bulk moduli (or acoustic speeds), or even double-negative transformation medium (i.e. both density and bulk modulus parameters are negative). With such sets of active acoustic metamaterials, the cloak and anti-cloak may become both theoretically and experimentally realizable. (paper)

Electromagnetic cloaking in higher order spherical cloaks

Science.gov (United States)

Sidhwa, H. H.; Aiyar, R. P. R. C.; Kulkarni, S. V.

2017-06-01

The inception of transformation optics has led to the realisation of the invisibility devices for various applications, one of which is spherical cloaking. In this paper, a formulation for a higher-order spherical cloak has been proposed to reduce its physical thickness significantly by introducing a nonlinear relation between the original and transformed coordinate systems and it has been verified using the ray tracing approach. Analysis has been carried out to observe the anomalies in the variation of refractive index for higher order cloaks indicating the presence of poles in the relevant equations. Furthermore, a higher-order spherical cloak with predefined values of the material characteristics on its inner and outer surfaces has been designed for practical application.

Design of a broadband ultra-large area acoustic cloak based on a fluid medium

Science.gov (United States)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

2014-10-01

A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

Temperature-Controlled Chameleonlike Cloak

Science.gov (United States)

Peng, Ruiguang; Xiao, Zongqi; Zhao, Qian; Zhang, Fuli; Meng, Yonggang; Li, Bo; Zhou, Ji; Fan, Yuancheng; Zhang, Peng; Shen, Nian-Hai; Koschny, Thomas; Soukoulis, Costas M.

2017-01-01

Invisibility cloaking based on transformation optics has brought about unlimited space for reverie. However, the design and fabrication of transformation-optics-based cloaks still remain fairly challenging because of the complicated, even extreme, material prescriptions, including its meticulously engineered anisotropy, inhomogeneity and singularity. And almost all the state-of-the-art cloaking devices work within a narrow and invariable frequency band. Here, we propose a novel mechanism for all-dielectric temperature-controllable cloaks. A prototype device was designed and fabricated with SrTiO3 ferroelectric cuboids as building blocks, and its cloaking effects were successfully demonstrated, including its frequency-agile invisibility by varying temperature. It revealed that the predesignated cloaking device based on our proposed strategy could be directly scaled in dimensions to operate at different frequency regions, without the necessity for further efforts of redesign. Our work opens the door towards the realization of tunable cloaking devices for various practical applications and provides a simple strategy to readily extend the cloaking band from microwave to terahertz regimes without the need for reconfiguration.

Temperature-Controlled Chameleonlike Cloak

Directory of Open Access Journals (Sweden)

Ruiguang Peng

2017-03-01

Full Text Available Invisibility cloaking based on transformation optics has brought about unlimited space for reverie. However, the design and fabrication of transformation-optics-based cloaks still remain fairly challenging because of the complicated, even extreme, material prescriptions, including its meticulously engineered anisotropy, inhomogeneity and singularity. And almost all the state-of-the-art cloaking devices work within a narrow and invariable frequency band. Here, we propose a novel mechanism for all-dielectric temperature-controllable cloaks. A prototype device was designed and fabricated with SrTiO_{3} ferroelectric cuboids as building blocks, and its cloaking effects were successfully demonstrated, including its frequency-agile invisibility by varying temperature. It revealed that the predesignated cloaking device based on our proposed strategy could be directly scaled in dimensions to operate at different frequency regions, without the necessity for further efforts of redesign. Our work opens the door towards the realization of tunable cloaking devices for various practical applications and provides a simple strategy to readily extend the cloaking band from microwave to terahertz regimes without the need for reconfiguration.

Categorization of new fractal carpets

International Nuclear Information System (INIS)

Rani, Mamta; Goel, Saurabh

2009-01-01

Sierpinski carpet is one of the very beautiful fractals from the historic gallery of classical fractals. Carpet designing is not only a fascinating activity in computer graphics, but it has real applications in carpet industry as well. One may find illusionary delighted carpets designed here, which are useful in real designing of carpets. In this paper, we attempt to systematize their generation and put them into categories. Each next category leads to a more generalized form of the fractal carpet.

Design of Nonwoven Carpets to Upgrade Sound Isolation Features in Automobiles

Directory of Open Access Journals (Sweden)

Atakan Raziye

2014-12-01

Full Text Available With the increases of the expected properties of textile products, better and advanced new designs are being created. Textiles used in vehicles are increasing, and the current performance of the expectations bar is determined by automobile manufacturers. While meeting the expectations of users in the vehicle mechanically, but also disturbing the user during operation of the mechanical properties of this ratio should be minimized. This study was intended to minimize sound transmission of nonwoven textile components, which are used in cars as silencer parts. For that purpose, four different models were developed in this study. First model consists of three designs for baggage carpets. Second model has six designs for floor coverings. Third model comprises two designs inner dash felt and finally fourth model includes two designs of hood liners. The acoustical absorption coefficients and transmission loss of these carpets were tested and evaluated in the frequency range of 16-6300 Hz. The measurements demonstrated that nonwoven layer is a very significant and effective part of a carpet due to its contribution in the sound isolation. With this study, it has been determined which layer has better performance on sound absorption and transmission loss among different carpet types. A combination of heavy layer and nonwoven layer carpets is found to be benefit for noise and sound insulation.

Enhanced Near-cloak by FSH Lining

OpenAIRE

Liu, Hongyu; Sun, Hongpeng

2011-01-01

We consider regularized approximate cloaking for the Helmholtz equation. Various cloaking schemes have been recently proposed and extensively investigated. The existing cloaking schemes in literature are (optimally) within $|\\ln\\rho|^{-1}$ in 2D and $\\rho$ in 3D of the perfect cloaking, where $\\rho$ denotes the regularization parameter. In this work, we develop a cloaking scheme with a well-designed lossy layer right outside the cloaked region that can produce significantly enhanced near-cloa...

Analysis of flexural wave cloaks

Directory of Open Access Journals (Sweden)

Alfonso Climente

2016-12-01

Full Text Available This work presents a comprehensive study of the cloak for bending waves theoretically proposed by Farhat et al. [see Phys. Rev. Lett. 103, 024301 (2009] and later on experimentally realized by Stenger et al. [see Phys. Rev. Lett. 108, 014301 (2012]. This study uses a semi-analytical approach, the multilayer scattering method, which is based in the Kirchoff-Love wave equation for flexural waves in thin plates. Our approach was unable to reproduce the predicted behavior of the theoretically proposed cloak. This disagreement is here explained in terms of the simplified wave equation employed in the cloak design, which employed unusual boundary conditions for the cloaking shell. However, our approach reproduces fairly well the measured displacement maps for the fabricated cloak, indicating the validity of our approach. Also, the cloak quality has been here analyzed using the so called averaged visibility and the scattering cross section. The results obtained from both analysis let us to conclude that there is room for further improvements of this type of flexural wave cloak by using better design procedures.

A multidirectional cloak for visible light

Science.gov (United States)

Chen, Zhen Sheng; Lei Mei, Zhong; Jiang, Wei Xiang; Cui, Tie Jun

2018-04-01

A new macroscopic multidirectional cloak scheme for extraordinary rays is proposed by controlling the optical axes of uniaxial crystals. It eliminates the complicated material constraints and can also be utilized to design a cloaking device for ordinary rays or isotropic cloaks after simplification. Numerical ray tracing and full-wave simulation results validate our design. Moreover, if the uniaxial crystals are changed into other materials whose optical axes can be modulated, like liquid crystals, this scheme has the potential to fabricate direction-tunable cloaks.

Cloaks with multiple invisible regions

International Nuclear Information System (INIS)

Luo, Yang; Zhu, Shouzheng; He, Lianxing; Wang, Yu

2011-01-01

This paper proposes a general method of extending the effective invisible regions for both the shell-like interior cloak and the complementary media exterior cloak, without affecting their original cloaking regions. The proposed method is based on layered spatial mapping instead of the intact mapping. Certain interior or exterior invisible regions can be obtained by properly using a compressed or folded transformation in each space layer. Therefore, the proposal enables the as-designed cloaks to provide multiple invisible regions of different types simultaneously. Thus objects can be hidden in the interior cavity and/or in the exterior space, or even be embedded between the cloaking shells

Homogenous isotropic invisible cloak based on geometrical optics.

Science.gov (United States)

Sun, Jingbo; Zhou, Ji; Kang, Lei

2008-10-27

Invisible cloak derived from the coordinate transformation requires its constitutive material to be anisotropic. In this work, we present a cloak of graded-index isotropic material based on the geometrical optics theory. The cloak is realized by concentric multilayered structure with designed refractive index to achieve the low-scattering and smooth power-flow. Full-wave simulations on such a design of a cylindrical cloak are performed to demonstrate the cloaking ability to incident wave of any polarization. Using normal nature material with isotropy and low absorption, the cloak shows light on a practical path to stealth technology, especially that in the optical range.

Experimental and computational studies of electromagnetic cloaking at microwaves

Science.gov (United States)

Wang, Xiaohui

An invisibility cloak is a device that can hide the target by enclosing it from the incident radiation. This intriguing device has attracted a lot of attention since it was first implemented at a microwave frequency in 2006. However, the problems of existing cloak designs prevent them from being widely applied in practice. In this dissertation, we try to remove or alleviate the three constraints for practical applications imposed by loosy cloaking media, high implementation complexity, and small size of hidden objects compared to the incident wavelength. To facilitate cloaking design and experimental characterization, several devices and relevant techniques for measuring the complex permittivity of dielectric materials at microwave frequencies are developed. In particular, a unique parallel plate waveguide chamber has been set up to automatically map the electromagnetic (EM) field distribution for wave propagation through the resonator arrays and cloaking structures. The total scattering cross section of the cloaking structures was derived based on the measured scattering field by using this apparatus. To overcome the adverse effects of lossy cloaking media, microwave cloaks composed of identical dielectric resonators made of low loss ceramic materials are designed and implemented. The effective permeability dispersion was provided by tailoring dielectric resonator filling fractions. The cloak performances had been verified by full-wave simulation of true multi-resonator structures and experimental measurements of the fabricated prototypes. With the aim to reduce the implementation complexity caused by metamaterials employment for cloaking, we proposed to design 2-D cylindrical cloaks and 3-D spherical cloaks by using multi-layer ordinary dielectric material (epsilon r>1) coating. Genetic algorithm was employed to optimize the dielectric profiles of the cloaking shells to provide the minimum scattering cross sections of the cloaked targets. The designed cloaks can

Arbitrarily elliptical-cylindrical invisible cloaking

International Nuclear Information System (INIS)

Jiang Weixiang; Cui Tiejun; Yu Guanxia; Lin Xianqi; Cheng Qiang; Chin, J Y

2008-01-01

Based on the idea of coordinate transformation (Pendry, Schurig and Smith 2006 Science 312 1780), arbitrarily elliptical-cylindrical cloaks are proposed and designed. The elliptical cloak, which is composed of inhomogeneous anisotropic metamaterials in an elliptical-shell region, will deflect incoming electromagnetic (EM) waves and guide them to propagate around the inner elliptical region. Such EM waves will return to their original propagation directions without distorting the waves outside the elliptical cloak. General formulations of the inhomogeneous and anisotropic permittivity and permeability tensors are derived for arbitrarily elliptical axis ratio k, which can also be used for the circular cloak when k = 1. Hence the elliptical cloaks can make a large range of objects invisible, from round objects (when k approaches 1) to long and thin objects (when k is either very large or very small). We also show that the material parameters in elliptical cloaking are singular at only two points, instead of on the whole inner circle for circular cloaking, which are much easier to be realized in actual applications. Full-wave simulations are given to validate the arbitrarily elliptical cloaking

Electromagnetic Invisibility of Elliptic Cylinder Cloaks

International Nuclear Information System (INIS)

Kan, Yao; Chao, Li; Fang, Li

2008-01-01

Structures with unique electromagnetic properties are designed based on the approach of spatial coordinate transformations of Maxwell's equations. This approach is applied to scheme out invisible elliptic cylinder cloaks, which provide more feasibility for cloaking arbitrarily shaped objects. The transformation expressions for the anisotropic material parameters and the field distribution are derived. The cloaking performances of ideal and lossy elliptic cylinder cloaks are investigated by finite element simulations. It is found that the cloaking performance will degrade in the forward direction with increasing loss. (fundamental areas of phenomenology (including applications))

Electronically cloaked nanoparticles

Science.gov (United States)

Shen, Wenqing

The concept of electronic cloaking is to design objects invisible to conduction electrons. The approach of electronic cloaking has been recently suggested to design invisible nanoparticle dopants with electronic scattering cross section smaller than 1% of the physical cross section (pi a2), and therefore to enhance the carrier mobility of bulk materials. The proposed nanoparticles have core-shell structures. The dopants are incorporated inside the core, while the shell layer serves both as a spacer to separate the charge carriers from their parent atoms and as a cloaking shell to minimize the scattering cross section of the electrons from the ionized nanoparticles. Thermoelectric materials are usually highly doped to have enough carrier density. Using invisible dopants could achieve larger thermoelectric power factors by enhancing the electronic mobility. Core-shell nanoparticles show an advantage over one-layer nanoparticles, which are proposed in three-dimensional modulation doping. However designing such nanoparticles is not easy as there are too many parameters to be considered. This thesis first shows an approach to design hollow nanoparticles by applying constrains on variables. In the second part, a simple mapping approach is introduced where one can identify possible core-shell particles by comparing the dimensionless parameters of chosen materials with provided maps. In both parts of this work, several designs with realistic materials were made and proven to achieve electronic cloaking. Improvement in the thermoelectric power factor compared to the traditional impurity doping method was demonstrated in several cases.

Transformation-based spherical cloaks designed by an implicit transformation-independent method: theory and optimization

International Nuclear Information System (INIS)

Novitsky, Andrey; Qiu, C-W; Zouhdi, Said

2009-01-01

Based on the concept of the cloak generating function, we propose an implicit transformation-independent method for the required parameters of spherical cloaks without knowing the needed coordinate transformation beforehand. A non-ideal discrete model is used to calculate and optimize the total scattering cross-sections of different profiles of the generating function. A bell-shaped quadratic spherical cloak is found to be the best candidate, which is further optimized by controlling the design parameters involved. Such improved invisibility is steady even when the model is highly discretized.

Elastodynamic cloaking and field enhancement for soft spheres

Science.gov (United States)

Diatta, Andre; Guenneau, Sebastien

2016-11-01

We propose a spherical cloak described by a non-singular asymmetric elasticity tensor {C} depending upon a small parameter η, that defines the softness of a region one would like to conceal from elastodynamic waves. By varying η, we generate a class of soft spheres dressed by elastodynamic cloaks, which are shown to considerably reduce the scattering of the soft spheres. Importantly, such cloaks also provide some wave protection except for a countable set of frequencies, for which some large elastic field enhancement can be observed within the soft spheres. Through an investigation of trapped modes in elasticity, we supply a good approximation of such Mie-type resonances by some transcendental equation. Our results, unlike previous studies that focused merely on the invisibility aspects, shed light on potential pitfalls of elastodynamic cloaks for earthquake protection designed via geometric transforms: a seismic cloak needs to be designed in such a way that its inner resonances differ from eigenfrequencies of the building one wishes to protect. In order to circumvent this downfall of field enhancement inside the cloaked area, we introduce a novel generation of cloaks, named here, mixed cloaks. Such mixed cloaks consist of a shell that detours incoming waves, hence creating an invisibility region, and of a perfectly matched layer (PML, located at the inner boundary of the cloaks) that absorbs residual wave energy in such a way that aforementioned resonances in the soft sphere are strongly attenuated. The designs of mixed cloaks with a non-singular elasticity tensor combined with an inner PML and non-vanishing density bring seismic cloaks one step closer to a practical implementation. Note in passing that the concept of mixed cloaks also applies in the case of singular cloaks and can be translated in other wave areas for a similar purpose (i.e. to smear down inner resonances within the invisibility region).

A multi-cloak bifunctional device

Science.gov (United States)

Raza, Muhammad; Liu, Yichao; Ma, Yungui

2015-01-01

Invisibility cloak has attracted the attention of electromagnetic researchers due to its magical properties and marvelous potential applications in the field of applied physics and engineering. Recently, a multiphysics cloaking has put the new spirit into this field. In this paper, we introduce a device, composed of three shells and each shell works as an invisibility cloak for a specific physical phenomenon. Following this technique, a number of cloaks with different implementation approaches can be proposed for distinct physical phenomena in a single structure. Here, we restrict ourselves for the case of two physical behaviors: thermal and electrical conductivities. This type of multi-cloaking structure can be best used in mechanically designed structures to better control heating and electrical effects.

Carpeting/Flooring: Revitalizing Carpets.

Science.gov (United States)

Woolford, Alison; Hill, Michael

2003-01-01

With properly specified fiber and a comprehensive maintenance program, school carpets can retain their appearance longer. Discusses carpet characteristics; proper carpet installation; effective preventive-maintenance programs (keep outside areas clean, use soil barriers, protect desk areas, maintain HVAC systems, and specify eating, drinking, and…

Metasurface Cloaks for Large Cylindrical Cluster Configurations

DEFF Research Database (Denmark)

Arslanagic, Samel; Yakovlev, A.B.

2014-01-01

Here, we investigate the performance of metasurfaces used for cloaking of cluster configurations formed by different arrangements of multiple dielectric cylinders and excited by an electric line source. While a suitably designed metasurface can be used to effectively cloak isolated electrically...... small cylinders, we demonstrate that even electrically large clusters of such particles can be cloaked by covering its constituent cylinders with the metasurface cloaks. This holds for densely packed cylinders due to significantly reduced coupling by the presence of the cloaks. The results may...

Electromagnetic cloaking devices for TE and TM polarizations

International Nuclear Information System (INIS)

Bilotti, Filiberto; Tricarico, Simone; Vegni, Lucio

2008-01-01

In this paper, we present the design of an electromagnetic cloaking device working for both transverse electric (TE) and transverse magnetic (TM) polarizations. The theoretical approach to cloaking used here is inspired by the one presented by Alu and Engheta (2005 Phys. Rev. E 72 016623) for TM polarization. The case of TE polarization is firstly considered and, then, an actual inclusion-based cloak for TE polarization is also designed. In such a case, the cloak is made of a mu-near-zero (MNZ) metamaterial, as the dual counterpart of the epsilon-near-zero (ENZ) material that can be used for purely dielectric objects. The operation and the robustness of the cloaking device for the TE polarization is deeply investigated through a complete set of full-wave numerical simulations. Finally, the design and an application of a cloak operating for both TE and TM polarizations employing both magnetic inclusions and the parallel plate medium already used by Silveirinha et al (Phys. Rev. E 75 036603) are presented.

Design of the Coordinate Transformation Function for Cylindrical Acoustic Cloaks with a Quantity of Discrete Layers

International Nuclear Information System (INIS)

Cai Li; Wen Ji-Hong; Yu Dian-Long; Lu Zhi-Miao; Wen Xi-Sen

2014-01-01

Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential applications such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transformation function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers. (fundamental areas of phenomenology(including applications))

Design of the Coordinate Transformation Function for Cylindrical Acoustic Cloaks with a Quantity of Discrete Layers

Science.gov (United States)

Cai, Li; Wen, Ji-Hong; Yu, Dian-Long; Lu, Zhi-Miao; Wen, Xi-Sen

2014-09-01

Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential applications such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transformation function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers.

A two-component NZRI metamaterial based rectangular cloak

Directory of Open Access Journals (Sweden)

Sikder Sunbeam Islam

2015-10-01

Full Text Available A new two-component, near zero refractive index (NZRI metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.

Ultrabroadband elastic cloaking in thin plates.

Science.gov (United States)

Farhat, Mohamed; Guenneau, Sebastien; Enoch, Stefan

2009-07-10

Control of waves with metamaterials is of great topical interest, and is fueled by rapid progress in broadband acoustic and electromagnetic cloaks. We propose a design for a cloak to control bending waves propagating in isotropic heterogeneous thin plates. This is achieved through homogenization of a multilayered concentric coating filled with piecewise constant isotropic elastic material. Significantly, our cloak displays no phase shift for both backward and forward scattering. To foster experimental efforts, we provide a simplified design of the cloak which is shown to work in a more than two-octave frequency range (30 Hz to 150 Hz) when it consists of 10 layers using only 6 different materials overall. This metamaterial should be easy to manufacture, with potential applications ranging from car industry to anti-earthquake passive systems for smart buildings, depending upon the plate dimensions and wavelengths.

A new metamaterial-based wideband rectangular invisibility cloak

Science.gov (United States)

Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.

2018-02-01

A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.

Topology optimized cloak for airborne sound

DEFF Research Database (Denmark)

Andkjær, Jacob Anders; Sigmund, Ole

2013-01-01

Directional acoustic cloaks that conceal an aluminum cylinder for airborne sound waves are presented in this paper. Subwavelength cylindrical aluminum inclusions in air constitute the cloak design to aid practical realizations. The positions and radii of the subwavelength cylinders are determined...

Two-dimensional arbitrarily shaped acoustic cloaks composed of homogeneous parts

Science.gov (United States)

Li, Qi; Vipperman, Jeffrey S.

2017-10-01

Acoustic cloaking is an important application of acoustic metamaterials. Although the topic has received much attention, there are a number of areas where contributions are needed. In this paper, a design method for producing acoustic cloaks with arbitrary shapes that are composed of homogeneous parts is presented. The cloak is divided into sections, each of which, in turn, is further divided into two parts, followed by the application of transformation acoustics to derive the required properties for cloaking. With the proposed mapping relations, the properties of each part of the cloak are anisotropic but homogeneous, which can be realized using two alternating layers of homogeneous and isotropic materials. A hexagonal and an irregular cloak are presented as design examples. The full wave simulations using COMSOL Multiphysics finite element software show that the cloaks function well at reducing reflections and shadows. The variation of the cloak properties is investigated as a function of three important geometric parameters used in the transformations. A balance can be found between cloaking performance and materials properties that are physically realizable.

Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials

International Nuclear Information System (INIS)

Yu Zhenzhong; Feng Yijun; Xu Xiaofei; Zhao Junming; Jiang Tian

2011-01-01

We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

Add-on unidirectional elastic metamaterial plate cloak

Science.gov (United States)

Lee, Min Kyung; Kim, Yoon Young

2016-02-01

Metamaterial cloaks control the propagation of waves to make an object invisible or insensible. To manipulate elastic waves in space, a metamaterial cloak is typically embedded in a base system that includes or surrounds a target object. The embedding is undesirable because it structurally weakens or permanently alters the base system. In this study, we propose a new add-on metamaterial elastic cloak that can be placed over and mechanically coupled with a base structure without embedding. We designed an add-on type annular metamaterial plate cloak through conformal mapping, fabricated it and performed cloaking experiments in a thin-plate with a hole. Experiments were performed in a thin plate by using the lowest symmetric Lamb wave centered at 100 kHz. As a means to check the cloaking performance of the add-on elastic plate cloak, possibly as a temporary stress reliever or a so-called “stress bandage”, the degree of stress concentration mitigation and the recovery from the perturbed wave field due to a hole were investigated.

Broadband three-dimensional diamond-shaped invisible cloaks composed of tetrahedral homogeneous blocks

International Nuclear Information System (INIS)

Wang Xinhua; Qu Shaobo; Wu Xiang; Wang Jiafu; Ma Hua; Xu Zhuo

2010-01-01

By means of embedded optical transformation, three-dimensional diamond-shaped invisible cloaks composed of tetrahedral homogeneous blocks have been designed in this paper. The constitutive parameters of the invisible cloaks can be obtained based on the form invariance of Maxwell's equations in coordinate transformation. Numerical methods using the finite element method verified the diamond-shaped cloaks. The invisible properties of the designed cloaks are nearly perfect when the original line section is sufficiently short compared with its counterpart in the after-transformed space. The designed cloaks can operate in a wide bandwidth due to the line transformation in the coordinate transformation process.

A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials

Science.gov (United States)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

2015-08-01

The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds.

Interior acoustic cloak

Directory of Open Access Journals (Sweden)

Wael Akl

2014-12-01

Full Text Available Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which are invariably heavy and bulky. The transformation acoustics relationships that govern the operation of this class of interior acoustic cloaks are presented. Physical insights are given to relate these relationships to the reasons behind the effectiveness of the proposed interior acoustic cloaks. Finite element models are presented to demonstrate the characteristics of interior acoustic cloaks used in treating the interior walls of circular and square cavities both in the time and frequency domains. The obtained results emphasize the effectiveness of the proposed interior cloaks in eliminating the reflections of the acoustic waves from the walls of the treated cavities and thereby rendering these cavities acoustically quiet. It is important to note here that the proposed interior acoustic cloaks can find applications in acoustic cavities such as aircraft cabins and auditoriums as well as many other critical applications.

A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials

International Nuclear Information System (INIS)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

2015-01-01

The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds. (paper)

Broadband unidirectional cloaks based on flat metasurface focusing lenses

International Nuclear Information System (INIS)

Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

2015-01-01

Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects. (paper)

Broadband unidirectional cloaks based on flat metasurface focusing lenses

Science.gov (United States)

Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

2015-08-01

Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects.

Analytical Solution for Elliptical Cloaks Based on The Frequency Selective Surface

Directory of Open Access Journals (Sweden)

E. Ghasemi Mizuji

2015-01-01

Full Text Available In this paper the elliptical dielectric cylinder which is covered with FSS cloak is considered. Frequency selective surface cloak which Alu named it mantle cloak is one of the recent techniques for cloaking. In this method an appropriate FSS can act as cloaking device for suppressing  the scattering of object  in the desired frequency. With using this method the dimension of the cloaks is extremely reduced. By this proposed structure, the RCS of elliptical cylinder  is reduced about 10-20 dB and designed cloak has an appropriate performance.  The analytical solution for the wave in each layer is presented and with using simulation, the electric field and the scattering pattern has been drawn.

OPTICAL ILLUSION DESIGN BASED ON FOUR CONVEX LENSES SYSTEM AND CLOAKING AREA CHARACTERIZATION

Directory of Open Access Journals (Sweden)

I. T. Sugiarto

2018-01-01

Full Text Available A set up of optical illusion based on 4f system and characterization of cloaking area have been carried out. The cloaking area is an area where the object is placed on the area as if it disappears from view; the set-up of cloaking area is located at the top of the third lens. The distance between the lens and the cloaking, which is generated from 4f system, depends on the size of the focal point and the size of the lens used. The larger the focal point of the lens used the wider the distance between the lenses and the larger the size of the diameter of the lens, the cloaking range will be increasingly wide, and vice versa. From the experimental results that we obtained that the cloaking area for set up using FL (focusing lens 100, 50, 50 and 100 mm with a diameter of 3.6 cm lens is ± 2 cm, whereas for the set up using lens FL 150, 100, 100 and 150 mm with lens diameter 2.54 cm is ± 1 cm.

Invisible anti-cloak with elliptic cross section using phase complement

International Nuclear Information System (INIS)

Yang Yu-Qi; Zhang Min; Yue Jian-Xiang

2011-01-01

Based on the theory of phase complement, an anti-cloak with circular cross section can be made invisible to an object outside its domain. As the cloak with elliptic cross section is more effective to make objects invisible than that with circular cross section, a scaled coordinate system is proposed to design equivalent materials of invisible anti-cloak with elliptic cross section using phase complement. The cloaks with conventional dielectric and double negative parameters are both simulated with the geometrical transformations. The results show that the cloak with elliptic cross section through phase complement can effectively hide the outside objects. (classical areas of phenomenology)

A hybrid Scatter/Transform cloaking model

Directory of Open Access Journals (Sweden)

Gad Licht

2015-01-01

Full Text Available A new Scatter/Transform cloak is developed that combines the light bending of refraction characteristic of a Transform cloak with the scatter cancellation characteristic of a Scatter cloak. The hybrid cloak incorporates both Transform’s variable index of refraction with modified linear intrusions to maximize the Scatter cloak effect. Scatter/Transform improved the scattering cross-section of cloaking in a 2-dimensional space to 51.7% compared to only 39.6% or 45.1% respectively with either Scatter or Transform alone. Metamaterials developed with characteristics based on the new ST hybrid cloak will exhibit superior cloaking capabilities.

Homogeneous optical cloak constructed with uniform layered structures

DEFF Research Database (Denmark)

Zhang, Jingjing; Liu, Liu; Luo, Yu

2011-01-01

, the majority of the invisibility cloaks reported so far have a spatially varying refractive index which requires complicated design processes. Besides, the size of the hidden object is usually small relative to that of the cloak device. Here we report the experimental realization of a homogenous invisibility...

Regular scattering patterns from near-cloaking devices and their implications for invisibility cloaking

International Nuclear Information System (INIS)

Kocyigit, Ilker; Liu, Hongyu; Sun, Hongpeng

2013-01-01

In this paper, we consider invisibility cloaking via the transformation optics approach through a ‘blow-up’ construction. An ideal cloak makes use of singular cloaking material. ‘Blow-up-a-small-region’ construction and ‘truncation-of-singularity’ construction are introduced to avoid the singular structure, however, giving only near-cloaks. The study in the literature is to develop various mechanisms in order to achieve high-accuracy approximate near-cloaking devices, and also from a practical viewpoint to nearly cloak an arbitrary content. We study the problem from a different viewpoint. It is shown that for those regularized cloaking devices, the corresponding scattering wave fields due to an incident plane wave have regular patterns. The regular patterns are both a curse and a blessing. On the one hand, the regular wave pattern betrays the location of a cloaking device which is an intrinsic defect due to the ‘blow-up’ construction, and this is particularly the case for the construction by employing a high-loss layer lining. Indeed, our numerical experiments show robust reconstructions of the location, even by implementing the phaseless cross-section data. The construction by employing a high-density layer lining shows a certain promising feature. On the other hand, it is shown that one can introduce an internal point source to produce the canceling scattering pattern to achieve a near-cloak of an arbitrary order of accuracy. (paper)

Enhanced approximate cloaking by optimal change of variables

International Nuclear Information System (INIS)

Griesmaier, Roland; Vogelius, Michael S

2014-01-01

The aim of (passive) cloaking with respect to electromagnetic (or acoustic) sensing is to surround a region of space with a material layer—the cloak—that renders its contents and even the existence of the layer undetectable by such measurements. At least theoretically this can be achieved using the coordinate invariance of the underlying wave equation, through so-called cloaking by mapping. However, a practical realization of the cloaking by mapping schemes discussed in the literature frequently requires the design of highly anisotropic materials with extreme dielectric properties. In this work we consider, in the electrostatic case, a regularized, approximate cloaking by mapping scheme and discuss the problem of optimal choice of radial maps, that determine the conductivity distribution of the cloak. We consider two different optimality criteria: minimal maximal anisotropy and minimal mean anisotropy of this conductivity distribution. Using both criteria we show that it is possible to achieve significantly lower anisotropy (for a prescribed level of invisibility) or significantly lower visibility (for a prescribed level of anisotropy). For example, in two dimensions one may achieve exponentially small visibility with a cloak, that in terms of anisotropy (and lowest and highest conductivity) is no worse than the traditional affine map cloak, which only yields quadratically small visibility. (paper)

Nonideal ultrathin mantle cloak for electrically large conducting cylinders.

Science.gov (United States)

Liu, Shuo; Zhang, Hao Chi; Xu, He-Xiu; Cui, Tie Jun

2014-09-01

Based on the concept of the scattering cancellation technique, we propose a nonideal ultrathin mantle cloak that can efficiently suppress the total scattering cross sections of an electrically large conducting cylinder (over one free-space wavelength). The cloaking mechanism is investigated in depth based on the Mie scattering theory and is simultaneously interpreted from the perspective of far-field bistatic scattering and near-field distributions. We remark that, unlike the perfect transformation-optics-based cloak, this nonideal cloaking technique is mainly designed to minimize simultaneously several scattering multipoles of a relatively large geometry around considerably broad bandwidth. Numerical simulations and experimental results show that the antiscattering ability of the metasurface gives rise to excellent total scattering reduction of the electrically large cylinder and remarkable electric-field restoration around the cloak. The outstanding cloaking performance together with the good features of and ultralow profile, flexibility, and easy fabrication predict promising applications in the microwave frequencies.

A self-assembled three-dimensional cloak in the visible

KAUST Repository

Mü hlig, Stefan; Cunningham, Alastair; Dintinger, José ; Farhat, Mohamed; Hasan, Shakeeb Bin; Scharf, Toralf; Bü rgi, Thomas; Lederer, Falk; Rockstuhl, Carsten

2013-01-01

An invisibility cloak has been designed, realized and characterized. The cloak hides free-standing sub-wavelength three-dimensional objects at the short wavelength edge of the visible spectrum. By a bottom-up approach the cloak was self-assembled around the object. Such fabrication approach constitutes a further important step towards real world applications of cloaking; leaving the realm of curiosity. The cloak and the way it was fabricated opens an avenue for many spectacular nanooptical applications such as non-disturbing sensors and photo-detectors, highly efficient solar cells, or optical nanoantenna arrays with strongly suppressed cross-talk to mention only a few. Our results rely on the successful combination of concepts from various disciplines, i.e. chemistry, material science, and plasmonics. Consequently, this work will stimulate these fields by unraveling new paths for future research.

A self-assembled three-dimensional cloak in the visible

KAUST Repository

Mühlig, Stefan

2013-08-07

An invisibility cloak has been designed, realized and characterized. The cloak hides free-standing sub-wavelength three-dimensional objects at the short wavelength edge of the visible spectrum. By a bottom-up approach the cloak was self-assembled around the object. Such fabrication approach constitutes a further important step towards real world applications of cloaking; leaving the realm of curiosity. The cloak and the way it was fabricated opens an avenue for many spectacular nanooptical applications such as non-disturbing sensors and photo-detectors, highly efficient solar cells, or optical nanoantenna arrays with strongly suppressed cross-talk to mention only a few. Our results rely on the successful combination of concepts from various disciplines, i.e. chemistry, material science, and plasmonics. Consequently, this work will stimulate these fields by unraveling new paths for future research.

2-D Fractal Carpet Antenna Design and Performance

Science.gov (United States)

Barton, C. C.; Tebbens, S. F.; Ewing, J. J.; Peterman, D. J.; Rizki, M. M.

2017-12-01

A 2-D fractal carpet antenna uses a fractal (self-similar) pattern to increase its perimeter by iteration and can receive or transmit electromagnetic radiation within its perimeter-bounded surface area. 2-D fractals are shapes that, at their mathematical limit (infinite iterations) have an infinite perimeter bounding a finite surface area. The fractal dimension describes the degree of space filling and lacunarity which quantifies the size and spatial distribution of open space bounded by a fractal shape. A key aspect of fractal antennas lies in iteration (repetition) of a fractal pattern over a range of length scales. Iteration produces fractal antennas that are very compact, wideband and multiband. As the number of iterations increases, the antenna operates at higher and higher frequencies. Manifestly different from traditional antenna designs, a fractal antenna can operate at multiple frequencies simultaneously. We have created a MATLAB code to generate deterministic and stochastic modes of Sierpinski carpet fractal antennas with a range of fractal dimensions between 1 and 2. Variation in fractal dimension, stochasticity, number of iterations, and lacunarities have been computationally tested using COMSOL Multiphysics software to determine their effect on antenna performance

Acoustic invisibility cloaks of arbitrary shapes for complex background media

Science.gov (United States)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

2016-04-01

We report on the theoretical investigation of the acoustic cloaks working in complex background media in this paper. The constitutive parameters of arbitrary-shape cloaks are derived based on the transformation acoustic theory and coordinate transformation technique. The detailed analysis of boundaries conditions and potential applications of the cloaks are also presented in our work. To overcome the difficulty of achieving the materials with ideal parameters in nature, concentric alternating layered isotropic materials is adopted to approximate the required properties of the cloak. Theoretical design and excellent invisibility are demonstrated by numerical simulations. The inhomogeneous medium and arbitrary-shape acoustic cloaks grow closer to real application and may be a new hot spot in future.

Static Magnetic Cloak without a Superconductor

Science.gov (United States)

Jiang, Wei; Ma, Yungui; He, Sailing

2018-05-01

Similar to its electromagnetic counterpart, magnetic cloaking also has very important technological applications. However, the traditional method to build a static magnetic cloak requires the use of superconducting materials as the diamagnetic component, which seriously limits the practical potential because of the cryogenic condition. We show that a diamagnetic active current boundary combined with a high-permeability magnetic inner shell (MIS) can be designed to solve this problem, rendering an ideal magnetic cloaking effect at zero frequency. We first theoretically prove that a current boundary could magnetically behave as a superconductor to external observers. Based on this phenomena, we introduce a high-permeability MIS made of magnetically ultrasoft metallic sheets (permeability μ >103 ) and experimentally prove that the bilayer combination can exactly balance out the disturbance to the external probing field and, meanwhile, have a large invisible inner space. We also show that the active boundary currents can be accordingly configured to overcome the permeability and frequency band limits, leading to a robust cloak over the entire quasistatic frequency region. Our work creates an efficient way to circumvent the traditional limits of metamaterials to build magnetic cloaks for ultralow frequencies. The active-passive hybrid approach could be generally extended to yield other artificial magnetic devices or systems as well.

Interior acoustic cloak

OpenAIRE

Wael Akl; A. Baz

2014-01-01

Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which a...

An intelligent and interactive carpet role of design in a textile innovation project

NARCIS (Netherlands)

Deckers, E.J.L.; Stouw, van der B.; Peutz, J.

2012-01-01

This paper presents an ongoing innovation project on the development of an intelligent and interactive carpet called PeR+, short for Perception Rug Plus. This design-research project is a collaboration between an international flooring company, DESSO, and the Department of Industrial Design at the

Acoustic cloaking and transformation acoustics

International Nuclear Information System (INIS)

Chen Huanyang; Chan, C T

2010-01-01

In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

Grating-Coupled Waveguide Cloaking

International Nuclear Information System (INIS)

Wang Jia-Fu; Qu Shao-Bo; Ma Hua; Wang Cong-Min; Wang Xin-Hua; Zhou Hang; Xu Zhuo; Xia Song

2012-01-01

Based on the concept of a grating-coupled waveguide (GCW), a new strategy for realizing EM cloaking is presented. Using metallic grating, incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind, enabling EM waves to pass around the obstacle. Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged. Circular, rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking. Electric field animations and radar cross section (RCS) comparisons convincingly demonstrate the cloaking effect

Material parameters characterization for arbitrary N-sided regular polygonal invisible cloak

International Nuclear Information System (INIS)

Wu Qun; Zhang Kuang; Meng Fanyi; Li Lewei

2009-01-01

Arbitrary N-sided regular polygonal cylindrical cloaks are proposed and designed based on the coordinate transformation theory. First, the general expressions of constitutive tensors of the N-sided regular polygonal cylindrical cloaks are derived, then there are some full-wave simulations of the cloaks that are composed of inhomogeneous and anisotropic metamaterials, which will bend incoming electromagnetic waves and guide them to propagate around the inner region; such electromagnetic waves will return to their original propagation directions without distorting the waves outside the polygonal cloak. The results of full-wave simulations validate the general expressions of constitutive tensors of the N-sided regular polygonal cylindrical cloaks we derived.

Experiments on Active Cloaking and Illusion for Laplace Equation

Science.gov (United States)

Ma, Qian; Mei, Zhong Lei; Zhu, Shou Kui; Jin, Tian Yu; Cui, Tie Jun

2013-10-01

In recent years, invisibility cloaks have received a lot of attention and interest. These devices are generally classified into two types: passive and active. The design and realization of passive cloaks have been intensively studied using transformation optics and plasmonic approaches. However, active cloaks are still limited to theory and numerical simulations. Here, we present the first experiment on active cloaking and propose an active illusion for the Laplace equation. We make use of a resistor network to simulate a conducting medium. Then, we surround the central region with controlled sources to protect it from outside detection. We show that by dynamically changing the controlled sources, the protected region can be cloaked or disguised as different objects (illusion). Our measurement results agree very well with numerical simulations. Compared with the passive counterparts, the active cloaking and illusion devices do not need complicated metamaterials. They are flexible, in-line controllable, and adaptable to the environment. In addition to dc electricity, the proposed method can also be used for thermodynamics and other problems governed by the Laplace equation.

The scattering of a cylindrical invisibility cloak: reduced parameters and optimization

DEFF Research Database (Denmark)

Peng, Liang; Ran, L.; Mortensen, Asger

2011-01-01

We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component...... of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak using some peculiar composites...

Broadband cloaking using composite dielectrics

Directory of Open Access Journals (Sweden)

Ruey-Bing Hwang

2011-03-01

Full Text Available In this paper, we present a novel cloaking structure that is able to make a metallic block invisible in a metallic waveguide. Such a cloak is made up of a stack of commonly used dielectric slabs. We carry out the numerical simulation and observe the detour of the vector Poynting power through the cloak. Moreover, the experiment is conducted for measuring the scattering characteristics including the reflection and transmission coefficients. The great improvement in the transmission coefficient in a broad bandwidth after cloaking is demonstrated. Significantly, the theory of mode conversion is developed for explaining the cloaking phenomenon.

Ray-optics cloaking devices for large objects in incoherent natural light

Science.gov (United States)

Chen, Hongsheng; Zheng, Bin; Shen, Lian; Wang, Huaping; Zhang, Xianmin; Zheludev, Nikolay I.; Zhang, Baile

2013-10-01

A cloak that can hide living creatures from sight is a common feature of mythology but still remains unrealized as a practical device. To preserve the wave phase, the previous cloaking solution proposed by Pendry and colleagues required transformation of the electromagnetic space around the hidden object in such a way that the rays bending around the object inside the cloak region have to travel faster than those passing it by. This difficult phase preservation requirement is the main obstacle for building a broadband polarization-insensitive cloak for large objects. Here we propose a simplified version of Pendry’s cloak by abolishing the requirement for phase preservation, as it is irrelevant for observation using incoherent natural light with human eyes, which are phase and polarization insensitive. This allows for a cloak design on large scales using commonly available materials. We successfully demonstrate the cloaking of living creatures, a cat and a fish, from the eye.

Acoustic cloaking in two dimensions: a feasible approach

Energy Technology Data Exchange (ETDEWEB)

Torrent, Daniel; Sanchez-Dehesa, Jose [Wave Phenomena Group, Department of Electronic Engineering, Polytechnic University of Valencia, C/ Camino de vera s.n., E-46022 Valencia (Spain)], E-mail: jsdehesa@upvnet.upv.es

2008-06-15

This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its fabrication.

Design and analysis of gradient index metamaterial-based cloak with wide bandwidth and physically realizable material parameters

Science.gov (United States)

Bisht, Mahesh Singh; Rajput, Archana; Srivastava, Kumar Vaibhav

2018-04-01

A cloak based on gradient index metamaterial (GIM) is proposed. Here, the GIM is used, for conversion of propagating waves into surface waves and vice versa, to get the cloaking effect. The cloak is made of metamaterial consisting of four supercells with each supercell possessing the linear spatial variation of permittivity and permeability. The spatial variation of material parameters in supercells allows the conversion of propagating waves into surface waves and vice versa, hence results in reduction of electromagnetic signature of the object. To facilitate the practical implementation of the cloak, continuous spatial variation of permittivity and/or permeability, in each supercell, is discretized into seven segments and it is shown that there is not much deviation in cloaking performance of discretized cloak as compared to its continuous counterpart. The crucial advantage, of the proposed cloaks, is that the material parameters are isotropic and in physically realizable range. Furthermore, the proposed cloaks have been shown to possess bandwidth of the order of 190% which is a significantly improved performance compared to the recently published literature.

Invisibility cloaking without superluminal propagation

Energy Technology Data Exchange (ETDEWEB)

Perczel, Janos; Leonhardt, Ulf [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Tyc, Tomas, E-mail: jp394@st-andrews.ac.uk, E-mail: tomtyc@physics.muni.cz, E-mail: ulf@st-andrews.ac.uk [Faculty of Science, Kotlarska 2 and Faculty of Informatics, Botanicka 68a, Masaryk University, 61137 Brno (Czech Republic)

2011-08-15

Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needs media with superluminal propagation. Here we show by giving an example that this is no longer necessary.

Detecting electromagnetic cloaks using backward-propagating waves

KAUST Repository

Salem, Mohamed; Bagci, Hakan

2011-01-01

A novel approach for detecting transformation-optics invisibility cloaks is proposed. The detection method takes advantage of the unusual backward-propagation characteristics of recently reported beams and pulses to induce electromagnetic scattering from the cloak. Even though waves with backward-propagating energy flux cannot penetrate the cloaking shell and interact with the cloaked objects (i.e., they do not make the cloaked object visible), they provide a mechanism for detecting the presence of cloaks. © 2011 IEEE.

Detecting electromagnetic cloaks using backward-propagating waves

KAUST Repository

Salem, Mohamed

2011-08-01

A novel approach for detecting transformation-optics invisibility cloaks is proposed. The detection method takes advantage of the unusual backward-propagation characteristics of recently reported beams and pulses to induce electromagnetic scattering from the cloak. Even though waves with backward-propagating energy flux cannot penetrate the cloaking shell and interact with the cloaked objects (i.e., they do not make the cloaked object visible), they provide a mechanism for detecting the presence of cloaks. © 2011 IEEE.

Geometry and Cloaking Devices

Science.gov (United States)

Ochiai, T.; Nacher, J. C.

2011-09-01

Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

Temperature controlled infrared broadband cloaking with the bilayer coatings of semiconductor and superconductor

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaohua [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Physics and Electronics, Yancheng Teachers University, Yancheng 224051 (China); Liu, Youwen, E-mail: ywliu@nuaa.edu.cn [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Feng, Yuncai [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2015-06-15

Highlights: • We first propose that the cloak is composed of the bilayer of semiconductor and superconductor. • We realize the infrared broadband cloaking based on the scattering cancellation method. • The cloaking frequency can be tuned by external temperature. - Abstract: The infrared broadband tunable cloaking have been proposed and investigated with the bilayer coating materials of semiconductor (n-Ge) and high-temperature superconductor (YBa{sub 2}Cu{sub 3}O{sub 7}), whose cloaking frequency can be controlled by external temperature. The analytical solution is derived based on the scattering cancellation cloaking technique from the Mie scattering theory, and the full-wave numerical simulation is performed by the finite element method. The calculated and simulated results have demonstrated that this invisibility cloak may reduce the total scattering cross section of the composite structure of 90% over a broad frequency band of nearly 20 THz, and the infrared cloaking frequency can be tuned by the external temperature. It can provide a feasible way to design a broadband tunable cloak.

An efficient cost function for the optimization of an n-layered isotropic cloaked cylinder

International Nuclear Information System (INIS)

Paul, Jason V; Collins, Peter J; Coutu, Ronald A Jr

2013-01-01

In this paper, we present an efficient cost function for optimizing n-layered isotropic cloaked cylinders. Cost function efficiency is achieved by extracting the expression for the angle independent scatterer contribution of an associated Green's function. Therefore, since this cost function is not a function of angle, accounting for every bistatic angle is not necessary and thus more efficient than other cost functions. With this general and efficient cost function, isotropic cloaked cylinders can be optimized for many layers and material parameters. To demonstrate this, optimized cloaked cylinders made of 10, 20 and 30 equal thickness layers are presented for TE and TM incidence. Furthermore, we study the effect layer thickness has on optimized cloaks by optimizing a 10 layer cloaked cylinder over the material parameters and individual layer thicknesses. The optimized material parameters in this effort do not exhibit the dual nature that is evident in the ideal transformation optics design. This indicates that the inevitable field penetration and subsequent PEC boundary condition at the cylinder must be taken into account for an optimal cloaked cylinder design. Furthermore, a more effective cloaked cylinder can be designed by optimizing both layer thickness and material parameters than by additional layers alone. (paper)

Diffusive-light invisibility cloak for transient illumination

Science.gov (United States)

Orazbayev, B.; Beruete, M.; Martínez, A.; García-Meca, C.

2016-12-01

Invisibility in a diffusive-light-scattering medium has been recently demonstrated by employing a scattering-cancellation core-shell cloak. Unlike nondiffusive cloaks, such a device can be simultaneously macroscopic, broadband, passive, polarization independent, and omnidirectional. Unfortunately, it has been verified that this cloak, as well as more sophisticated ones based on transformation optics, fail under pulsed illumination, invalidating their use for a variety of applications. Here, we introduce a different approach based on unimodular transformations that enables the construction of unidirectional diffusive-light cloaks exhibiting a perfect invisibility effect, even under transient conditions. Moreover, we demonstrate that a polygonal cloak can extend this functionality to multiple directions with a nearly ideal behavior, while preserving all other features. We propose and numerically verify a simple cloak realization based on a layered stack of two isotropic materials. The studied devices have several applications not addressable by any of the other cloaks proposed to date, including shielding from pulse-based detection techniques, cloaking undesired scattering elements in time-of-flight imaging or high-speed communication systems for diffusive environments, and building extreme optical security features. The discussed cloaking strategy could also be applied to simplify the implementation of thermal cloaks.

On three-dimensional spherical acoustic cloaking

International Nuclear Information System (INIS)

Munteanu, Ligia; Chiroiu, Veturia

2011-01-01

Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.

Magnetically controlled multifrequency invisibility cloak with a single shell of ferrite material

Science.gov (United States)

Wang, Xiaohua; Liu, Youwen

2015-02-01

A magnetically controlled multifrequency invisibility cloak with a single shell of the isotropic and homogeneous ferrite material has been investigated based on the scattering cancellation method from the Mie scattering theory. The analytical and simulated results have demonstrated that such this shell can drastically reduce the total scattering cross-section of this cloaking system at multiple frequencies. These multiple cloaking frequencies of this shell can be externally controlled since the magnetic permeability of ferrites is well tuned by the applied magnetic field. This may provide a potential way to design a tunable multifrequency invisibility cloak with considerable flexibility.

Broadband unidirectional acoustic cloak based on phase gradient metasurfaces with two flat acoustic lenses

Science.gov (United States)

Wang, Xiao-Peng; Wan, Le-Le; Chen, Tian-Ning; Song, Ai-Ling; Wang, Fang

2016-07-01

Narrow bandwidth and bulky configuration are the main obstacles for the realization and application of invisible cloaks. In this paper, we present an effective method to achieve broadband and thin acoustic cloak by using an acoustic metasurface (AMS). In order to realize this cloak, we use slitted unit cells to design the AMS due to the advantage of less energy loss, broad operation bandwidth, and subwavelength thickness. According to the hyperboloidal phase profile along the AMS, the incident plane waves can be focused at a designed focal spot by the flat lens. Furthermore, broadband acoustic cloak is obtained by combining two identical flat lenses. The incident plane waves are focused at the center point in between of the two lenses by passing through one lens, and then recovered by passing through the other one. However, they cannot reach the cloaked regions in between of the two lenses. The simulation results can verify the non-detectability effect of the acoustic cloak. Our study results provide an available and simple approach to experimentally achieve the acoustic cloak, which can be used in acoustic non-detectability for large objects.

7 CFR 2902.34 - Carpet and upholstery cleaners.

Science.gov (United States)

2010-01-01

... procurement applies are: (i) General purpose cleaners. Carpet and upholstery cleaners formulated for use in... PROCUREMENT Designated Items § 2902.34 Carpet and upholstery cleaners. (a) Definition. (1) Cleaning products... upholstery cleaners shall be based on the amount of qualifying biobased carbon in the product as a percent of...

The scattering of a cylindrical invisibility cloak: reduced parameters and optimization

International Nuclear Information System (INIS)

Peng, L; Mortensen, N A; Ran, L

2011-01-01

We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak using some peculiar composites such as photonic crystals which mimic an effective refractive index landscape rather than offering effective constitutives, meanwhile cancelling the scattering from the inner and outer boundaries.

Asymmetric Invisibility Cloaking Theory Based on the Concept of Effective Electromagnetic Fields for Photons

Science.gov (United States)

Amemiya, Tomo; Taki, Masato; Kanazawa, Toru; Arai, Shigehisa

2014-03-01

The asymmetric invisibility cloak is a special cloak with unidirectional transparency; that is, a person in the cloak should not be seen from the outside but should be able to see the outside. Existing theories of designing invisibility cloaks cannot be used for asymmetric cloaking because they are based on the transformation optics that uses Riemannian metric tensor independent of direction. To overcome this problem, we propose introducing directionality into invisibility cloaking. Our theory is based on ``the theory of effective magnetic field for photons'' proposed by Stanford University.[2] To realize asymmetric cloaking, we have extended the Stanford's theory to add the concept of ``effective electric field for photons.'' The effective electric and the magnetic field can be generated using a photonc resonator lattice, which is a kind of metamaterial. The Hamiltonian for photons in these fields has a similar form to that of the Hamiltonian for a charged particle in an electromagnetic field. An incident photon therefore experiences a ``Lorentz-like'' and a ``Coulomb-like'' force and shows asymmetric movement depending of its travelling direction.We show the procedure of designing actual invisibility cloaks using the photonc resonator lattice and confirm their operation with the aid of computer simulation. This work was supported in part by the MEXT; JSPS KAKENHI Grant Numbers #24246061, #24656046, #25420321, #25420322.

Do Cloaked Objects Really Scatter Less?

Directory of Open Access Journals (Sweden)

Francesco Monticone

2013-10-01

Full Text Available We discuss the global scattering response of invisibility cloaks over the entire electromagnetic spectrum, from static to very high frequencies. Based on linearity, causality, and energy conservation, we show that the total extinction and scattering, integrated over all wavelengths, of any linear, passive, causal, and nondiamagnetic cloak, necessarily increase compared to the uncloaked case. In light of this general principle, we provide a quantitative measure to compare the global performance of different cloaking techniques and we discuss solutions to minimize the global scattering signature of an object using thin, superconducting shells. Our results provide important physical insights on how invisibility cloaks operate and affect the global scattering of an object, suggesting ways to defeat countermeasures aimed at detecting cloaked objects using short impinging pulses.

Enhanced approximate cloaking by SH and FSH lining

International Nuclear Information System (INIS)

Li, Jingzhi; Liu, Hongyu; Sun, Hongpeng

2012-01-01

We consider approximate cloaking from a regularization viewpoint introduced in Kohn et al (2008 Inverse Problems 24 015016) for EIT and further investigated in Kohn et al (2010 Commun. Pure Appl. Math. 63 0973–1016) and Liu (2009 Inverse Problems 25 045006) for the Helmholtz equation. The cloaking schemes given by Kohn et al and Liu are shown to be (optimally) within |ln ρ| −1 in 2D and ρ in 3D of perfect cloaking, where ρ denotes the regularization parameter. In this paper, we show that by employing a sound-hard layer right outside the cloaked region, one could (optimally) achieve ρ N in R N , N ≥ 2, which significantly enhances the near-cloak. We then develop a cloaking scheme by making use of a lossy layer with well-chosen parameters. The lossy-layer cloaking scheme is shown to possess the same cloaking performance as the one with a sound-hard layer. Moreover, it is shown that the lossy layer could be taken as a finite realization of the sound-hard layer. Numerical experiments are also presented to assess the cloaking performances of all the cloaking schemes for comparisons. (paper)

Mantle cloaking for co-site radio-frequency antennas

Energy Technology Data Exchange (ETDEWEB)

Monti, Alessio, E-mail: alessio.monti@uniroma3.it; Barbuto, Mirko [“Niccolò Cusano” University, Via Don Carlo Gnocchi 3, Rome 00166 (Italy); Soric, Jason; Alù, Andrea [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Ramaccia, Davide; Vellucci, Stefano; Toscano, Alessandro; Bilotti, Filiberto [Department of Engineering, “Roma Tre” University, Via Vito Volterra 62, Rome 00146 (Italy); Trotta, Fabrizio [Antenna Department, ELETTRONICA S.p.A., Via Tiburtina Valeria Km 13700, Rome 00131 (Italy)

2016-03-14

We show that properly designed mantle cloaks, consisting of patterned metallic sheets placed around cylindrical monopoles, allow tightly packing the same antennas together in a highly dense telecommunication platform. Our experimental demonstration is applied to the relevant example of two cylindrical monopole radiators operating for 3G and 4G mobile communications. The two antennas are placed in close proximity, separated by 1/10 of the shorter operational wavelength, and, after cloaking, are shown to remarkably operate as if isolated in free-space. This result paves the way to unprecedented co-siting strategies for multiple antennas handling different services and installed in overcrowded platforms, such as communication towers, satellite payloads, aircrafts, or ship trees. More broadly, this work presents a significant application of cloaking technology to improve the efficiency of modern communication systems.

Mantle cloaking for co-site radio-frequency antennas

International Nuclear Information System (INIS)

Monti, Alessio; Barbuto, Mirko; Soric, Jason; Alù, Andrea; Ramaccia, Davide; Vellucci, Stefano; Toscano, Alessandro; Bilotti, Filiberto; Trotta, Fabrizio

2016-01-01

We show that properly designed mantle cloaks, consisting of patterned metallic sheets placed around cylindrical monopoles, allow tightly packing the same antennas together in a highly dense telecommunication platform. Our experimental demonstration is applied to the relevant example of two cylindrical monopole radiators operating for 3G and 4G mobile communications. The two antennas are placed in close proximity, separated by 1/10 of the shorter operational wavelength, and, after cloaking, are shown to remarkably operate as if isolated in free-space. This result paves the way to unprecedented co-siting strategies for multiple antennas handling different services and installed in overcrowded platforms, such as communication towers, satellite payloads, aircrafts, or ship trees. More broadly, this work presents a significant application of cloaking technology to improve the efficiency of modern communication systems.

Theory and potentials of multi-layered plasmonic covers for multi-frequency cloaking

International Nuclear Information System (INIS)

Alu, Andrea; Engheta, Nader

2008-01-01

We have recently suggested that suitably designed plasmonic layers may cloak a given object simultaneously at multiple frequencies (Alu and Engheta 2008 Phys. Rev. Lett. 100 113901). Here, we extend our theory and fully analyze this possibility, highlighting the potentials of this plasmonic cloaking technique and its fundamental limitations dictated by the passivity and causality of the materials involved. The cloaking mechanism relies on the scattering cancellation properties of plasmonic materials. By exploiting their inherent frequency dispersion, it is possible to reduce the 'visibility' of a given object by several orders of magnitude simultaneously at multiple frequencies, such that any of the particular layers composing the cloak is responsible for noticeable reduction of scattering at each frequency of operation.

Experimental demonstration of illusion optics with ``external cloaking'' effects

Science.gov (United States)

Li, Chao; Liu, Xiao; Liu, Guochang; Li, Fang; Fang, Guangyou

2011-08-01

A metamaterial "illusion optics" with "complementary medium" and "restoring medium" is designed by using inductor-capacitor (L-C) network medium. The unprecedented effects of "external cloaking" and "transforming one object to appear as another" are demonstrated experimentally. We also demonstrate that the non-resonant nature of the L-C network decreases the sensitivity of the "external cloaking" effect to the variation of the frequency and results in an acceptable bandwidth of the whole device.

Shoulder girdle muscle activity and fatigue in traditional and improved design carpet weaving workstations.

Science.gov (United States)

Allahyari, Teimour; Mortazavi, Narges; Khalkhali, Hamid Reza; Sanjari, Mohammad Ali

2016-01-01

Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10). Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Fourier analysis: from cloaking to imaging

Science.gov (United States)

Wu, Kedi; Cheng, Qiluan; Wang, Guo Ping

2016-04-01

Regarding invisibility cloaks as an optical imaging system, we present a Fourier approach to analytically unify both Pendry cloaks and complementary media-based invisibility cloaks into one kind of cloak. By synthesizing different transfer functions, we can construct different devices to realize a series of interesting functions such as hiding objects (events), creating illusions, and performing perfect imaging. In this article, we give a brief review on recent works of applying Fourier approach to analysis invisibility cloaks and optical imaging through scattering layers. We show that, to construct devices to conceal an object, no constructive materials with extreme properties are required, making most, if not all, of the above functions realizable by using naturally occurring materials. As instances, we experimentally verify a method of directionally hiding distant objects and create illusions by using all-dielectric materials, and further demonstrate a non-invasive method of imaging objects completely hidden by scattering layers.

Invisibility cloak with image projection capability.

Science.gov (United States)

Banerjee, Debasish; Ji, Chengang; Iizuka, Hideo

2016-12-13

Investigations of invisibility cloaks have been led by rigorous theories and such cloak structures, in general, require extreme material parameters. Consequently, it is challenging to realize them, particularly in the full visible region. Due to the insensitivity of human eyes to the polarization and phase of light, cloaking a large object in the full visible region has been recently realized by a simplified theory. Here, we experimentally demonstrate a device concept where a large object can be concealed in a cloak structure and at the same time any images can be projected through it by utilizing a distinctively different approach; the cloaking via one polarization and the image projection via the other orthogonal polarization. Our device structure consists of commercially available optical components such as polarizers and mirrors, and therefore, provides a significant further step towards practical application scenarios such as transparent devices and see-through displays.

A spacetime cloak, or a history editor

Science.gov (United States)

McCall, Martin W.; Favaro, Alberto; Kinsler, Paul; Boardman, Allan

2011-02-01

We introduce a new type of electromagnetic cloak, the spacetime cloak (STC), which conceals events rather than objects. Non-emitting events occurring during a restricted period are never suspected by a distant observer. The cloak works by locally manipulating the speed of light of an initially uniform light distribution, whilst the light rays themselves always follow straight paths. Any 'perfect' spacetime cloak would necessarily rely upon the technology of electromagnetic metamaterials, which has already been shown to be capable of deforming light in ways hitherto unforeseen—to produce, for example, an electromagnetic object cloak. Nevertheless, we show how it is possible to use intensity-dependent refractive indices to construct an approximate STC, an implementation that would enable the distinct signature of successful event cloaking to be observed. Potential demonstrations include systems that apparently violate quantum statistics, 'interrupt-without-interrupt' computation on convergent data channels and the illusion of a Star Trek transporter.

A spacetime cloak, or a history editor

International Nuclear Information System (INIS)

McCall, Martin W; Favaro, Alberto; Kinsler, Paul; Boardman, Allan

2011-01-01

We introduce a new type of electromagnetic cloak, the spacetime cloak (STC), which conceals events rather than objects. Non-emitting events occurring during a restricted period are never suspected by a distant observer. The cloak works by locally manipulating the speed of light of an initially uniform light distribution, whilst the light rays themselves always follow straight paths. Any 'perfect' spacetime cloak would necessarily rely upon the technology of electromagnetic metamaterials, which has already been shown to be capable of deforming light in ways hitherto unforeseen—to produce, for example, an electromagnetic object cloak. Nevertheless, we show how it is possible to use intensity-dependent refractive indices to construct an approximate STC, an implementation that would enable the distinct signature of successful event cloaking to be observed. Potential demonstrations include systems that apparently violate quantum statistics, 'interrupt-without-interrupt' computation on convergent data channels and the illusion of a Star Trek transporter

Transformation optics and invisibility cloaks

DEFF Research Database (Denmark)

Qiu, Min; Yan, Min; Yan, Wei

2008-01-01

In this paper, we briefly summarize the theory of transformation optics and introduce its application in achieving perfect invisibility cloaking. In particular, we theoretically show how the task of realizing cylindrical invisibility cloaks can be eased by using either structural approximation...

Fourier analysis: from cloaking to imaging

International Nuclear Information System (INIS)

Wu, Kedi; Ping Wang, Guo; Cheng, Qiluan

2016-01-01

Regarding invisibility cloaks as an optical imaging system, we present a Fourier approach to analytically unify both Pendry cloaks and complementary media-based invisibility cloaks into one kind of cloak. By synthesizing different transfer functions, we can construct different devices to realize a series of interesting functions such as hiding objects (events), creating illusions, and performing perfect imaging. In this article, we give a brief review on recent works of applying Fourier approach to analysis invisibility cloaks and optical imaging through scattering layers. We show that, to construct devices to conceal an object, no constructive materials with extreme properties are required, making most, if not all, of the above functions realizable by using naturally occurring materials. As instances, we experimentally verify a method of directionally hiding distant objects and create illusions by using all-dielectric materials, and further demonstrate a non-invasive method of imaging objects completely hidden by scattering layers. (review)

Prospects for poor-man's cloaking with low-contrast all-dielectric optical elements

DEFF Research Database (Denmark)

Mortensen, Asger; Sigmund, Ole; Breinbjerg, Olav

2009-01-01

We discuss the prospects for low-contrast all-dielectric cloaking and offer a simple picture illustrating the basic obstacle for perfect cloaking without materials with an effective double-negative response. However, the same simple picture also gives directions for less perfect designs allowing ......-lens arrays perform in the opposite limit with L l...

A rigorous analysis of high-order electromagnetic invisibility cloaks

International Nuclear Information System (INIS)

Weder, Ricardo

2008-01-01

There is currently a great deal of interest in the invisibility cloaks recently proposed by Pendry et al that are based on the transformation approach. They obtained their results using first-order transformations. In recent papers, Hendi et al and Cai et al considered invisibility cloaks with high-order transformations. In this paper, we study high-order electromagnetic invisibility cloaks in transformation media obtained by high-order transformations from general anisotropic media. We consider the case where there is a finite number of spherical cloaks located in different points in space. We prove that for any incident plane wave, at any frequency, the scattered wave is identically zero. We also consider the scattering of finite-energy wave packets. We prove that the scattering matrix is the identity, i.e., that for any incoming wave packet the outgoing wave packet is the same as the incoming one. This proves that the invisibility cloaks cannot be detected in any scattering experiment with electromagnetic waves in high-order transformation media, and in particular in the first-order transformation media of Pendry et al. We also prove that the high-order invisibility cloaks, as well as the first-order ones, cloak passive and active devices. The cloaked objects completely decouple from the exterior. Actually, the cloaking outside is independent of what is inside the cloaked objects. The electromagnetic waves inside the cloaked objects cannot leave the concealed regions and vice versa, the electromagnetic waves outside the cloaked objects cannot go inside the concealed regions. As we prove our results for media that are obtained by transformation from general anisotropic materials, we prove that it is possible to cloak objects inside general crystals

Coordinate transformations and matter waves cloaking

International Nuclear Information System (INIS)

Mohammadi, G.R.; Moghaddam, A.G.; Mohammadkhani, R.

2016-01-01

Transformation method provides an efficient tool to control wave propagation inside the materials. Using the coordinate transformation approach, we study invisibility cloaks with sphere, cylinder and ellipsoid structures for electronic waves propagation. The underlying physics behind this investigation is the fact that Schrödinger equation with position dependent mass tensor and potentials has a covariant form which follows the coordinate transformation. Using this technique we obtain the exact spatial form of the mass tensor and potentials for a variety of cloaks with different shapes. - Highlights: • Invisibility cloaks for matter waves with three different geometries. • Exact analytical form of the effective mass tensor and potential. • Analogy between cloaking for quantum mechanical waves with classical electromagnetic waves. • Possible experimental realization in engineered semiconducting structures.

The boundary conditions for point transformed electromagnetic invisibility cloaks

International Nuclear Information System (INIS)

Weder, Ricardo

2008-01-01

In this paper we study point transformed electromagnetic invisibility cloaks in transformation media that are obtained by transformation from general anisotropic media. We assume that there are several point transformed electromagnetic cloaks located in different points in space. Our results apply in particular to the first-order invisibility cloaks introduced by Pendry et al and to the high-order invisibility cloaks introduced by Hendi et al and by Cai et al. We identify the appropriate cloaking boundary conditions that the solutions of Maxwell equations have to satisfy at the outside, ∂K + , and at the inside, ∂K - , of the boundary of the cloaked object K in the case where the permittivity and the permeability are bounded below and above in K. Namely, that the tangential components of the electric and the magnetic fields have to vanish at ∂K + -which is always true-and that the normal components of the curl of the electric and the magnetic fields have to vanish at ∂K - . These results are proven requiring that energy be conserved. In the case of one spherical cloak with a spherically stratified K and a radial current at ∂K we verify by an explicit calculation that our cloaking boundary conditions are satisfied and that cloaking of active devices holds, even if the current is at the boundary of the cloaked object. As we prove our results for media that are obtained by transformation from general anisotropic media, our results apply to the cloaking of objects with passive and active devices contained in general anisotropic media, in particular to objects with passive and active devices contained inside general crystals. Our results suggest a method to enhance cloaking in the approximate transformation media that are used in practice. Namely, to coat the boundary of the cloaked object (the inner boundary of the cloak) with a material that imposes the boundary conditions above. As these boundary conditions have to be satisfied for exact transformation

Invisibility cloaking via non-smooth transformation optics and ray tracing

International Nuclear Information System (INIS)

Crosskey, Miles M.; Nixon, Andrew T.; Schick, Leland M.; Kovacic, Gregor

2011-01-01

We present examples of theoretically-predicted invisibility cloaks with shapes other than spheres and cylinders, including cones and ellipsoids, as well as shapes spliced from parts of these simpler shapes. In addition, we present an example explicitly displaying the non-uniqueness of invisibility cloaks of the same shape. We depict rays propagating through these example cloaks using ray tracing for geometric optics. - Highlights: → Theoretically-predicted conical and ellipsoidal invisibility cloaks. → Non-smooth cloaks spliced from parts of simpler shapes. → Example displaying non-uniqueness of invisibility cloaks of the same shape. → Rays propagating through example cloaks depicted using geometric optics.

Gravitational lensing as a mechanism for effective cloaking

International Nuclear Information System (INIS)

Tippett, Benjamin K.

2011-01-01

In light of the surge in popularity of electromagnetic cloaking devices, we consider whether it is possible to use general relativity to cloak a volume of spacetime through gravitational lensing. We explore the cloaking properties of a spacetime through a ray-tracing procedure, wherein we plot the spatial trajectories of a congruence of initially parallel null geodesics as they cross the geometry. In this context, a cloaking device would cause all of the null geodesics in an initially parallel congruence incident upon the cloaking geometry to circumnavigate an internal region, and as the geodesics emerge from the geometry, they regain their original configuration. Thus, if gravitational lensing were used as a mechanism for cloaking, the internal region would be causally isolated from the external spacetime. For this reason, we propose an effective cloaking geometry wherein (only) most of ingoing null geodesics will splay away from a central region, and then regain their initial configuration as they exit the geometry. Thus, a compact object sitting within the effective cloaking geometry will impede a smaller cross section of the null congruence, and therefore appear optically smaller from all sides. We build our effective cloaking geometry by connecting a Minkowski spacetime exterior to a spherically symmetric, curved spacetime along a timelike hypersurface of constant radius using the Israel junction conditions. The junction conditions require a shell of matter of infinitesimal width confined to the junction surface. The matter required to build such a spacetime must violate the null energy condition.

Coordinate transformations make perfect invisibility cloaks with arbitrary shape

International Nuclear Information System (INIS)

Yan Wei; Yan Min; Ruan Zhichao; Qiu Min

2008-01-01

By investigating wave properties at cloak boundaries, invisibility cloaks with arbitrary shape constructed by general coordinate transformations are confirmed to be perfectly invisible to the external incident wave. The differences between line transformed cloaks and point transformed cloaks are discussed. The fields in the cloak medium are found analytically to be related to the fields in the original space via coordinate transformation functions. At the exterior boundary of the cloak, it is shown that no reflection is excited even though the permittivity and permeability do not always have a perfectly matched layer form, whereas at the inner boundary, no reflection is excited either, and in particular no field can penetrate into the cloaked region. However, for the inner boundary of any line transformed cloak, the permittivity and permeability in a specific tangential direction are always required to be infinitely large. Furthermore, the field discontinuity at the inner boundary always exists; the surface current is induced to make this discontinuity self-consistent. A point transformed cloak does not experience such problems. The tangential fields at the inner boundary are all zero, implying that no field discontinuity exists

Towards all-dielectric, polarization-independent optical cloaks

DEFF Research Database (Denmark)

Andkjær, Jacob Anders; Mortensen, N. Asger; Sigmund, Ole

2012-01-01

Fully enclosing, all-dielectric cloaks working for both E-z and H-z polarizations simultaneously are presented in this letter. The cloaks are effective for two antiparallel angles of incidence, and the layout of standard dielectric material in the cloak is determined by topology optimization. Sca...... effectively when distributing a material with lower permittivity than the background material....

Galactic optical cloaking of visible baryonic matter

Science.gov (United States)

Smolyaninov, Igor I.

2018-05-01

Three-dimensional gravitational cloaking is known to require exotic matter and energy sources, which makes it arguably physically unrealizable. On the other hand, typical astronomical observations are performed using one-dimensional paraxial line of sight geometries. We demonstrate that unidirectional line of sight gravitational cloaking does not require exotic matter, and it may occur in multiple natural astronomical scenarios that involve gravitational lensing. In particular, recently discovered double gravitational lens SDSSJ 0 9 4 6 +1 0 0 6 together with the Milky Way appear to form a natural paraxial cloak. A natural question to ask, then, is how much matter in the Universe may be hidden from view by such natural gravitational cloaks? It is estimated that the total volume hidden from an observer by gravitational cloaking may reach about 1% of the total volume of the visible Universe.

Experimental demonstration of invisible electromagnetic impedance matching cylindrical transformation optics cloak shell

Science.gov (United States)

Chen, Mingji; Wang, Changxian; Cheng, Xiaodong; Gong, Congcheng; Song, Weili; Yuan, Xujin; Fang, Daining

2018-04-01

The realization of an ideal invisible cloak implementing transformation optics is still missing. An impedance matching concept is implanted into transformation optics cloak to generate an impedance matching cloak (IMC) shell. In this work, it is proved that impedance matching structure reduces the cloaking structure’s disturbance to a propagating electromagnetic field and improves its invisibility measured by scattering field intensity. Such a cylindrical IMC shell is designed, fabricated with proposed rounded rectangular split-ring-resonators (RR-SRRs), and experimental measurements show the total scattering field of a perfect electric conductor (PEC) cylinder surrounded by an IMC shell is improved greatly compared to the PEC cylinder showing electromagnetic wave front ripple suppression and a considerable scattering shrinking effect. IMC shell backward scattering field is suppressed down to 7.29%, compared to the previous value of 86.7% due to its impedance matching character, and overall scattering field intensity shrinking is down to 19.3% compared to the previously realized value of 56.4%. Sideward scattering field recorded in the experiment also has a remarkable improvement compared to the PEC cylinder. The impedance matching concept might enlighten the realization of an ideal cloak and other novel electromagnetic cloaking and shielding structures.

Anti-sound and Acoustical Cloaks

Directory of Open Access Journals (Sweden)

Veturia CHIROIU

2016-12-01

Full Text Available The principles by which the acoustics can be mimicked in order to reduce or cancel the vibrational field are based on anti-sound concept which can be materialized by acoustic cloaks. Geometric transformations open an elegant way towards the unconstrained control of sound through acoustic metamaterials. Acoustic cloaks can be achieved through geometric transformations which bring exotic metamaterial properties into the acoustic equations. Our paper brings new ideas concerning the technological keys for manufacturing of novel metamaterials based on the spatial compression of Cantor structures, and the architecture of 3D acoustic cloaks in a given frequency band, with application to architectural acoustics.

Molding acoustic, electromagnetic and water waves with a single cloak.

Science.gov (United States)

Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

2015-06-09

We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves.

Molding acoustic, electromagnetic and water waves with a single cloak

KAUST Repository

Xu, Jun

2015-06-09

We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. © 2015, Nature Publishing Group. All rights reserved.

Molding acoustic, electromagnetic and water waves with a single cloak

KAUST Repository

Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sé bastien

2015-01-01

We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. © 2015, Nature Publishing Group. All rights reserved.

Increasing the density of passive photonic-integrated circuits via nanophotonic cloaking

Science.gov (United States)

Shen, Bing; Polson, Randy; Menon, Rajesh

2016-11-01

Photonic-integrated devices need to be adequately spaced apart to prevent signal cross-talk. This fundamentally limits their packing density. Here we report the use of nanophotonic cloaking to render neighbouring devices invisible to one another, which allows them to be placed closer together than is otherwise feasible. Specifically, we experimentally demonstrated waveguides that are spaced by a distance of ~λ0/2 and designed waveguides with centre-to-centre spacing as small as 600 nm (-2 dB and an extinction ratio >15 dB over a bandwidth larger than 60 nm. This performance can be improved with better design algorithms and industry-standard lithography. The nanophotonic cloak relies on multiple guided-mode resonances, which render such devices very robust to fabrication errors. Our devices are broadly complimentary-metal-oxide-semiconductor compatible, have a minimum pitch of 200 nm and can be fabricated with a single lithography step. The nanophotonic cloaks can be generally applied to all passive integrated photonics.

Increasing the density of passive photonic-integrated circuits via nanophotonic cloaking.

Science.gov (United States)

Shen, Bing; Polson, Randy; Menon, Rajesh

2016-11-09

Photonic-integrated devices need to be adequately spaced apart to prevent signal cross-talk. This fundamentally limits their packing density. Here we report the use of nanophotonic cloaking to render neighbouring devices invisible to one another, which allows them to be placed closer together than is otherwise feasible. Specifically, we experimentally demonstrated waveguides that are spaced by a distance of ∼λ 0 /2 and designed waveguides with centre-to-centre spacing as small as 600 nm (-2 dB and an extinction ratio >15 dB over a bandwidth larger than 60 nm. This performance can be improved with better design algorithms and industry-standard lithography. The nanophotonic cloak relies on multiple guided-mode resonances, which render such devices very robust to fabrication errors. Our devices are broadly complimentary-metal-oxide-semiconductor compatible, have a minimum pitch of 200 nm and can be fabricated with a single lithography step. The nanophotonic cloaks can be generally applied to all passive integrated photonics.

Non-contact radio frequency shielding and wave guiding by multi-folded transformation optics method.

Science.gov (United States)

Madni, Hamza Ahmad; Zheng, Bin; Yang, Yihao; Wang, Huaping; Zhang, Xianmin; Yin, Wenyan; Li, Erping; Chen, Hongsheng

2016-11-14

Compared with conventional radio frequency (RF) shielding methods in which the conductive coating material encloses the circuits design and the leakage problem occurs due to the gap in such conductive material, non-contact RF shielding at a distance is very promising but still impossible to achieve so far. In this paper, a multi-folded transformation optics method is proposed to design a non-contact device for RF shielding. This "open-shielded" device can shield any object at a distance from the electromagnetic waves at the operating frequency, while the object is still physically open to the outer space. Based on this, an open-carpet cloak is proposed and the functionality of the open-carpet cloak is demonstrated. Furthermore, we investigate a scheme of non-contact wave guiding to remotely control the propagation of surface waves over any obstacles. The flexibilities of such multi-folded transformation optics method demonstrate the powerfulness of the method in the design of novel remote devices with impressive new functionalities.

A magnetic field cloak for charged particle beams

Science.gov (United States)

Capobianco-Hogan, K. G.; Cervantes, R.; Deshpande, A.; Feege, N.; Krahulik, T.; LaBounty, J.; Sekelsky, R.; Adhyatman, A.; Arrowsmith-Kron, G.; Coe, B.; Dehmelt, K.; Hemmick, T. K.; Jeffas, S.; LaByer, T.; Mahmud, S.; Oliveira, A.; Quadri, A.; Sharma, K.; Tishelman-Charny, A.

2018-01-01

Shielding charged particle beams from transverse magnetic fields is a common challenge for particle accelerators and experiments. We demonstrate that a magnetic field cloak is a viable solution. It allows for the use of dipole magnets in the forward regions of experiments at an Electron Ion Collider (EIC) and other facilities without interfering with the incoming beams. The dipoles can improve the momentum measurements of charged final state particles at angles close to the beam line and therefore increase the physics reach of these experiments. In contrast to other magnetic shielding options (such as active coils), a cloak requires no external powering. We discuss the design parameters, fabrication, and limitations of a magnetic field cloak and demonstrate that cylinders made from 45 layers of YBCO high-temperature superconductor, combined with a ferromagnetic shell made from epoxy and stainless steel powder, shield more than 99% of a transverse magnetic field of up to 0.45 T (95% shielding at 0.5 T) at liquid nitrogen temperature. The ferromagnetic shell reduces field distortions caused by the superconductor alone by 90% at 0.45 T.

Removal of Perfluorocarboxylic Acids (PFCAs) from Carpets Treated with Stain-protection Products by Using Carpet Cleaning Machines

Science.gov (United States)

PFCAs are found in a variety of consumer products, including, but not limited to, treated clothing and textiles, floor care products, paper containers for food, and carpets. For example, carpet that has been treated with stain-protection, carpet-care solutions, either by the manu...

Cloaking through cancellation of diffusive wave scattering

KAUST Repository

Farhat, Mohamed

2016-08-10

A new cloaking mechanism, which makes enclosed objects invisible to diffusive photon density waves, is proposed. First, diffusive scattering from a basic core-shell geometry, which represents the cloaked structure, is studied. The conditions of scattering cancellation in a quasi-static scattering regime are derived. These allow for tailoring the diffusivity constant of the shell enclosing the object so that the fields scattered from the shell and the object cancel each other. This means that the photon flow outside the cloak behaves as if the cloaked object were not present. Diffusive light invisibility may have potential applications in hiding hot spots in infrared thermography or tissue imaging. © 2016 The Author(s) Published by the Royal Society. All rights reserved.

Demonstration of an ultralow profile cloak for scattering suppression of a finite-length rod in free space

International Nuclear Information System (INIS)

Soric, J C; Chen, P Y; Alù, A; Kerkhoff, A; Rainwater, D; Melin, K

2013-01-01

We present the first experimental realization and verification of a three-dimensional stand-alone mantle cloak designed to suppress the total scattering of a finite-length dielectric rod of moderate cross-section. Mantle cloaking has been proposed to realize ultralow-profile conformal covers that may achieve substantial camouflage, transparency and high-performance non-invasive near-field sensing. Here, we realize and verify a mantle cloak for radio-waves. We report an extensive campaign of far- and near-field free-space measurements demonstrating that conformal cloaks can indeed produce strong scattering suppression in all directions and over a relatively broad bandwidth of operation. (paper)

Mantle cloaks for elliptical cylinders excited by an electric line source

DEFF Research Database (Denmark)

Kaminski, Piotr Marek; Yakovlev, Alexander B.; Arslanagic, Samel

2016-01-01

We investigate the ability of surface impedance mantle cloaks for cloaking of elliptical cylinders excited by an electric line source. The exact analytical solution of the problem utilizing Mathieu functions is obtained and is used to derive optimal surface impedances to cloak a number of configu......We investigate the ability of surface impedance mantle cloaks for cloaking of elliptical cylinders excited by an electric line source. The exact analytical solution of the problem utilizing Mathieu functions is obtained and is used to derive optimal surface impedances to cloak a number...

Isotropic and anisotropic surface wave cloaking techniques

International Nuclear Information System (INIS)

McManus, T M; Spada, L La; Hao, Y

2016-01-01

In this paper we compare two different approaches for surface waves cloaking. The first technique is a unique application of Fermat’s principle and requires isotropic material properties, but owing to its derivation is limited in its applicability. The second technique utilises a geometrical optics approximation for dealing with rays bound to a two dimensional surface and requires anisotropic material properties, though it can be used to cloak any smooth surface. We analytically derive the surface wave scattering behaviour for both cloak techniques when applied to a rotationally symmetric surface deformation. Furthermore, we simulate both using a commercially available full-wave electromagnetic solver and demonstrate a good level of agreement with their analytically derived solutions. Our analytical solutions and simulations provide a complete and concise overview of two different surface wave cloaking techniques. (paper)

Isotropic and anisotropic surface wave cloaking techniques

Science.gov (United States)

McManus, T. M.; La Spada, L.; Hao, Y.

2016-04-01

In this paper we compare two different approaches for surface waves cloaking. The first technique is a unique application of Fermat’s principle and requires isotropic material properties, but owing to its derivation is limited in its applicability. The second technique utilises a geometrical optics approximation for dealing with rays bound to a two dimensional surface and requires anisotropic material properties, though it can be used to cloak any smooth surface. We analytically derive the surface wave scattering behaviour for both cloak techniques when applied to a rotationally symmetric surface deformation. Furthermore, we simulate both using a commercially available full-wave electromagnetic solver and demonstrate a good level of agreement with their analytically derived solutions. Our analytical solutions and simulations provide a complete and concise overview of two different surface wave cloaking techniques.

Effect of One Carpet Weaving Workstation on Upper Trapezius Fatigue

Directory of Open Access Journals (Sweden)

Neda Mahdavi

2016-03-01

Full Text Available Introduction: This study aimed to investigate the effect of carpet weaving at a proposed workstation on Upper Trapezius (UTr fatigue during a task cycle. Fatigue in the shoulder is one of the most important precursors for upper limb musculoskeletal disorders. One of the most prevalent musculoskeletal disorders between carpet weavers is disorder of the shoulder region. Methods: This cross-sectional study, included eight females and three males. During an 80-minute cycle of carpet weaving, Electromyography (EMG signals of right and left UTr were recorded by the surface EMG, continuously. After raw signals were processed, MPF and RMS were considered as EMG amplitude and frequency parameters. Time series model and JASA methods were used to assess and classify the EMG parameter changes during the working time. Results: According to the JASA method, 58%, 16%, 8% and 8% of the participants experienced fatigue, force increase, force decrease and recovery, respectively in the right UTr. Also, 50%, 25%, 8% and 16% of the participants experienced fatigue, force increase, force decrease and recovery, respectively in the left UTr. Conclusions: For the major portion of the weavers, dominant status in Left and right UTr was fatigue, at the proposed workstation during a carpet weaving task cycle. The results of the study provide detailed information for optimal design of workstations. Further studies should focus on fatigue in various muscles and time periods for designing an appropriate and ergonomics carpet weaving workstation

Invisibility cloaks with arbitrary geometries for layered and gradually changing backgrounds

International Nuclear Information System (INIS)

Li, C; Yao, K; Li, F

2009-01-01

Cloaks with arbitrary geometries are proposed which can make objects invisible in inhomogeneous backgrounds. The general and explicit expressions of the complex permittivity and permeability tensors are derived for cloaks embedded in layered and gradually changing media. The inner and the outer boundaries of the cloaks can be non-conformal with arbitrary shapes, which considerably improve the flexibility of the cloak applications. The interactions of electromagnetic waves with irregular cloaks are studied based on numerical simulations. The influences of the cloaked and uncloaked perfect electric conductor (PEC) cylinders upon the scattering fields of the multilayered backgrounds are quantitatively evaluated. The effect of loss on the cloaking performance has also been investigated. It is verified that cloaks with ideal parameters can smoothly deflect and guide the incoming beams to propagate around the shielded regions without disturbing the beams when they return to the inhomogeneous backgrounds. Therefore, the objects in the shielded region can be effectively invisible to the corresponding backgrounds. The performance of lossy cloaks will degrade with comparatively large power reduction of the transmitted beams.

Spatial dispersion of index components required for building invisibility cloak medium from photonic crystals

Science.gov (United States)

Jamilan, Saeid; Semouchkin, George; Gandji, Navid P.; Semouchkina, Elena

2018-04-01

The opportunities to use dielectric photonic crystals (PhCs) as the media of cylindrical invisibility cloaks, designed using transformation optics (TO) concepts, are investigated. It is shown that TO-based prescriptions for radial index dispersion, responsible for turning waves around hidden objects, can be dropped if the PhC media support self-collimation of waves in bent crystals. Otherwise, to provide prescribed anisotropy of index dispersion, it is possible to employ PhCs with rectangular lattices. It is found, however, that at acceptable cloak thicknesses, modifications of crystal parameters do not allow for achieving the prescribed level of index anisotropy. This problem is solved by finding the reduced spatial dispersion law for the radial index component, which is characterized by decreased against TO-prescriptions values near the target and increased values in outer layers of the cloak. The cloak utilizing reduced prescriptions for indices is shown to perform almost as efficiently as a TO-based cloak, in terms of both wave front restoration behind the target and reducing the total scattering cross-width of the target.

Optical force on a discrete invisibility cloak in time-dependent fields

International Nuclear Information System (INIS)

Chaumet, Patrick C.; Zolla, Frederic; Nicolet, Andre; Belkebir, Kamal; Rahmani, Adel

2011-01-01

We study, in time domain, the exchange of momentum between an electromagnetic pulse and a three-dimensional, discrete, spherical invisibility cloak. We find that a discrete cloak, initially at rest, would experience an electromagnetic force due to the pulse but would acquire zero net momentum and net displacement. On the other hand, we find that while the cloak may manage to conceal an object and shroud it from the electromagnetic forces associated with the pulse, the cloak itself can experience optomechanical stress on a scale much larger than the object would in the absence of the cloak. We also consider the effects of material dispersion and losses on the electromagnetic forces experienced by the cloak and show that they lead to a transfer of momentum from the pulse to the cloak.

Minimizing the scattering of a nonmagnetic cloak

DEFF Research Database (Denmark)

Zhang, Jingjing; Luo, Yu; Mortensen, Asger

2010-01-01

Nonmagnetic cloak offers a feasible way to achieve invisibility at optical frequencies using materials with only electric responses. In this letter, we suggest an approximation of the ideal nonmagnetic cloak and quantitatively study its electromagnetic characteristics using a full-wave scattering...

Manipulating the loss in electromagnetic cloaks for perfect wave absorption.

Science.gov (United States)

Argyropoulos, Christos; Kallos, Efthymios; Zhao, Yan; Hao, Yang

2009-05-11

We examine several ways to manipulate the loss in electro-magnetic cloaks, based on transformation electromagnetics. It is found that, by utilizing inherent electric and magnetic losses of metamaterials, perfect wave absorption can be achieved based on several popular designs of electromagnetic cloaks. A practical implementation of the absorber, consisting of ten discrete layers of metamaterials, is proposed. The new devices demonstrate super-absorptivity over a moderate wideband range, suitable for both microwave and optical applications. It is corroborated that the device is functional with a subwavelength thickness and, hence, advantageous compared to the conventional absorbers.

The Real Dirt on Carpets.

Science.gov (United States)

Lang, Susan S.

2001-01-01

Argues that carpets do not contribute to student complaints of respiratory problems, allergies, and asthma as long as they are properly cleaned with high-efficiency microfiltration bags. Discusses contributions to mite problems made by smooth floor covering compared to carpeting. (GR)

EDITORIAL: Focus on Cloaking and Transformation Optics

Science.gov (United States)

Leonhardt, Ulf; Smith, David R.

2008-11-01

multi-frequency cloaking Andrea Alù and Nader Engheta Electromagnetic cloaking devices for TE and TM polarizations Filiberto Bilotti, Simone Tricarico and Lucio Vegni An aberration-free lens with zero F-number D Schurig Transformational optics of plasmonic metamaterials I I Smolyaninov An acoustic metafluid: realizing a broadband acoustic cloak J B Pendry and Jensen Li On the possibility of metamaterial properties in spin plasmas G Brodin and M Marklund A homogenization route towards square cylindrical acoustic cloaks Mohamed Farhat, Sébastien Guenneau, Stefan Enoch, Alexander Movchan, Frédéric Zolla and André Nicolet Transformation optics: approaching broadband electromagnetic cloaking A V Kildishev, W Cai, U K Chettiar and V M Shalaev Generalized field-transforming metamaterials Sergei A Tretyakov, Igor S Nefedov and Pekka Alitalo Electromagnetic beam modulation through transformation optical structures Xiaofei Xu, Yijun Feng and Tian Jiang Superantenna made of transformation media Ulf Leonhardt and Tomáš Tyc Material parameters and vector scaling in transformation acoustics Steven A Cummer, Marco Rahm and David Schurig Isotropic transformation optics: approximate acoustic and quantum cloaking Allan Greenleaf, Yaroslav Kurylev, Matti Lassas and Gunther Uhlmann Transformation optical designs for wave collimators, flat lenses and right-angle bends Do-Hoon Kwon and Douglas H Werner Alternative derivation of electromagnetic cloaks and concentrators A D Yaghjian and S Maci Solutions in folded geometries, and associated cloaking due to anomalous resonance Graeme W Milton, Nicolae-Alexandru P Nicorovici, Ross C McPhedran, Kirill Cherednichenko and Zubin Jacob Finite wavelength cloaking by plasmonic resonance N-A P Nicorovici, R C McPhedran, S Enoch and G Tayeb

Electromagnetic Detection of a Perfect Invisibility Cloak

International Nuclear Information System (INIS)

Zhang Baile; Wu, Bae-Ian

2009-01-01

A perfect invisibility cloak is commonly believed to be undetectable from electromagnetic (EM) detection because it is equivalent to a curved but empty EM space created from coordinate transformation. Based on the intrinsic asymmetry of coordinate transformation applied to motions of photons and charges, we propose a method to detect this curved EM space by shooting a fast-moving charged particle through it. A broadband radiation generated in this process makes a cloak visible. Our method is the only known EM mechanism so far to detect an ideal perfect cloak (curved EM space) within its working band.

A 3D tunable and multi-frequency graphene plasmonic cloak

KAUST Repository

Farhat, Mohamed

2013-01-01

We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers are doped via a variable external voltage difference permitting continuous tuning of the cloaking frequencies. Particularly, two configurations are investigated: (i) Only one graphene layer is used to suppress the scattering from a dielectric sphere. (ii) Several of these layers biased at different gate voltages are used to achieve a multi-frequency cloak. These frequencies can be set independently. The proposed cloak\\'s functionality is verified by near- and far-field computations. By considering geometry and material parameters that are realizable by practical experiments, we contribute to the development of graphene based plasmonic applications that may find use in disruptive photonic technologies. © 2013 Optical Society of America.

Rigorous analysis of non-magnetic cloaks

DEFF Research Database (Denmark)

Zhang, Jingjing; Luo, Yu; Mortensen, Asger

2010-01-01

Nonmagnetic cloak offers a feasible way to achieve invisibility at optical frequencies using materials with only electric responses. In this letter, we suggest an approximation of the ideal nonmagnetic cloak and quantitatively study its electromagnetic characteristics using a full-wave scattering...... to the surrounding material at the outer boundary. Our analysis also provides the flexibility of reducing the scattering in an arbitrary direction....

Level Set-Based Topology Optimization for the Design of an Electromagnetic Cloak With Ferrite Material

DEFF Research Database (Denmark)

Otomori, Masaki; Yamada, Takayuki; Andkjær, Jacob Anders

2013-01-01

. A level set-based topology optimization method incorporating a fictitious interface energy is used to find optimized configurations of the ferrite material. The numerical results demonstrate that the optimization successfully found an appropriate ferrite configuration that functions as an electromagnetic......This paper presents a structural optimization method for the design of an electromagnetic cloak made of ferrite material. Ferrite materials exhibit a frequency-dependent degree of permeability, due to a magnetic resonance phenomenon that can be altered by changing the magnitude of an externally...

Dispersive finite-difference time-domain (FDTD) analysis of the elliptic cylindrical cloak

Energy Technology Data Exchange (ETDEWEB)

Lee, Y. Y.; Ahn, D. [University of Seoul, Seoul (Korea, Republic of)

2012-05-15

A dispersive full-wave finite-difference time-domain (FDTD) model is used to calculate the performance of elliptic cylindrical cloaking devices. The permittivity and the permeability tensors for the cloaking structure are derived by using an effective medium approach in general relativity. The elliptic cylindrical invisibility devices are found to show imperfect cloaking, and the cloaking performance is found to depend on the polarization of the incident waves, the direction of the propagation of those waves, the semi-focal distances and the loss tangents of the meta-material. When the semifocal distance of the elliptic cylinder decreases, the performance of the cloaking becomes very good, with neither noticeable scatterings nor field penetrations. For a larger semi-focal distance, only the TM wave with a specific propagation direction shows good cloaking performance. Realistic cloaking materials with loss still show a cloak that is working, but attenuated back-scattering waves exist.

Possibility of perfect concealment by lossy conventional and lossy metamaterial cylindrical invisibility cloaks

Science.gov (United States)

Dehbashi, Reza; Shahabadi, Mahmoud

2013-12-01

The commonly used coordinate transformation for cylindrical cloaks is generalized. This transformation is utilized to determine an anisotropic inhomogeneous diagonal material tensors of a shell type cloak for various material types, i.e., double-positive (DPS: ɛ, μ > 0), double-negative (DNG: ɛ, μ cloaking for various material types, a rigorous analysis is performed. It is shown that perfect cloaking will be achieved for same type material for the cloak and its surrounding medium. Moreover, material losses are included in the analysis to demonstrate that perfect cloaking for lossy materials can be achieved for identical loss tangent of the cloak and its surrounding material. Sensitivity of the cloaking performance to losses for different material types is also investigated. The obtained analytical results are verified using a Finite-Element computational analysis.

Splitting of a vertical multiwalled carbon nanotube carpet to a graphene nanoribbon carpet and its use in supercapacitors.

Science.gov (United States)

Zhang, Chenguang; Peng, Zhiwei; Lin, Jian; Zhu, Yu; Ruan, Gedeng; Hwang, Chih-Chau; Lu, Wei; Hauge, Robert H; Tour, James M

2013-06-25

Potassium vapor was used to longitudinally split vertically aligned multiwalled carbon nanotubes carpets (VA-CNTs). The resulting structures have a carpet of partially split MWCNTs and graphene nanoribbons (GNRs). The split structures were characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. When compared to the original VA-CNTs carpet, the split VA-CNTs carpet has enhanced electrochemical performance with better specific capacitance in a supercapacitor. Furthermore, the split VA-CNTs carpet has excellent cyclability as a supercapacitor electrode material. There is a measured maximum power density of 103 kW/kg at an energy density of 5.2 Wh/kg and a maximum energy density of 9.4 Wh/kg. The superior electrochemical performances of the split VA-CNTs can be attributed to the increased surface area for ion accessibility after splitting, and the lasting conductivity of the structure with their vertical conductive paths based on the preserved GNR alignment.

Elliptical metasurfaces for cloaking and antenna applications at microwave and terahertz frequencies

Science.gov (United States)

Mehrpourbernety, Hossein

One of the interesting applications of metamaterials is the phenomenon of electromagnetic invisibility and cloaking, which implies the suppression of bistatic scattering width of a given object, independent of incident and observation angles. In this regard, diverse techniques have been proposed to analyze and design electromagnetic cloak structures, including transformation optics, anomalous resonance methods, transmission-line networks, and plasmonic cloaking, among others. A common drawback of all these methods is that they rely on bulk materials, which are difficult to realize in practice. To overcome this issue, the mantle cloaking method has been proposed, which utilizes an ultrathin metasurface that provides anti-phase surface currents to reduce the scattering dominant mode of a given object. Recently, an analytical model has been proposed to cloak dielectric and conducting cylindrical objects realized with printed and slotted arrays at microwave frequencies. At low-terahertz (THz) frequencies, one of the promising materials to realize the required metasurface is graphene. In this regard, a graphene monolayer, characterized by inductive reactance, has been proposed to cloak dielectric planar and cylindrical objects. Then, it has been shown that a metasurface made of graphene nanopatches owns dual capacitive/inductive inductance and can be used to cloak both dielectric and conducting cylindrical objects at low-THz frequencies. So far, planar and cylindrical dielectric and conducting structures have been studied. In our study, we have extended the concept and presented an accurate analytical approach to investigate the cloaking of two-dimensional (2-D) elliptical objects including infinite dielectric elliptical cylinders using graphene monolayer; metallic elliptical cylinders, and also, as a special case, 2-D metallic strips using a nanostructured graphene patch array at low-THz frequencies. We have also obtained the results for cloaking of ellipses at

Metamaterials beyond electromagnetism

International Nuclear Information System (INIS)

Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

2013-01-01

Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks. (review article)

Metamaterials beyond electromagnetism

Science.gov (United States)

Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

2013-12-01

Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

Illusions and Cloaks for Surface Waves

Science.gov (United States)

McManus, T. M.; Valiente-Kroon, J. A.; Horsley, S. A. R.; Hao, Y.

2014-08-01

Ever since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks.

Impact of home carpets on childhood lead intervention study

International Nuclear Information System (INIS)

Yiin, L.-M.; Lioy, P.J.; Rhoads, G.G.

2003-01-01

Blood lead data for a childhood lead exposure study have been reanalyzed to examine the impact of carpets on the effectiveness of a cleaning intervention in 39 New Jersey urban houses. All eligible houses in the study were classified as carpeted and uncarpeted depending on the number of rooms that were carpeted. The cleaning protocol was associated with a significant reduction in the blood lead concentrations for the uncarpeted homes (P=0.004), whereas no significant change was found for the carpeted homes (P=0.566). We also completed correlation analyses between the number of cleaning visits and the percentage reduction in blood lead for the carpeted/uncarpeted houses. There was a significant correlation (r=0.67) between the number of cleanings and blood lead reduction for the uncarpeted homes, but no correlation (r=0.04) for the carpeted homes. In a multiple regression model that took confounding variables into account, the carpet status (carpeted or uncarpeted) remained a factor of the effect of cleaning on blood lead (P=0.05). We conclude that the presence of contaminated carpets inhibits the effectiveness of home cleaning despite a high-efficiency particulate air filtered vacuum protocol that removes a substantial amount of lead dust

Impact of carpet construction on fluid penetration: The case of blood.

Science.gov (United States)

Feng, Chengcheng; Michielsen, Stephen; Attinger, Daniel

2018-03-01

Bloodstains and bloodstain patterns are often observed at crime scenes and their analysis through bloodstain pattern analysis (BPA) can assist in reconstructing crime scenes. However, most published work related to BPA only deals with hard, non-porous surfaces and none of the studies have carefully characterized carpets. Soft and porous carpets are often encountered at crime scenes since they are common in American homes accounting for 51% of total U.S. flooring market; this has motivated the research described herein. To assess fluid penetration into tufted carpers, a new method for determining porosity and pore size distribution in tufted carpets has been developed for bloodstains on carpet. In this study, three kinds of nylon carpet were used: a low, a medium and a high face-weight carpet. Each carpet had an antistain treatment, which was removed from half of each carpet by steam-cleaning with a pH 12 NaOH solution. This resulted in six carpet samples. Yarn twist, carpet weight, pile height, water contact angles on carpets, water contact angles on individual fibers, and fiber cross-sectional shapes were characterized. Porosity and pore size distribution were analyzed using confocal laser scanning microscopy (CLSM). Porcine blood was used as a human blood substitute at three liquid volumes (30μL, 10μL, and 2μL). Analysis showed that porous carpet construction and antistain finishing both affected penetration. The depth of blood penetration decreased with the increase of carpet face-weight but increased with increased drop height. The removal of antistain treatment increased blood penetration into the carpets and changed the pore size distribution. Effects of antistain treatment, porosity and pore size distribution of tufted carpet, and blood wicking behaviors on carpets were found to strongly affect blood penetration into the carpets. Copyright © 2018 Elsevier B.V. All rights reserved.

Invisibility Cloaking Based on Geometrical Optics for Visible Light

Science.gov (United States)

Ichikawa, H.; Oura, M.; Taoda, T.

2013-06-01

Optical cloaking has been one of unattainable dreams and just a subject in fiction until recently. Several different approaches to cloaking have been proposed and demonstrated: stealth technology, active camouflage and transformation optics. The last one would be the most formal approach modifying electromagnetic field around an object to be cloaked with metamaterials. While cloaking based on transformation optics, though valid only at single frequency, is experimentally demonstrated in microwave region, its operation in visible spectrum is still distant from realisation mainly owing to difficulty in fabricating metamaterial structure whose elements are much smaller than wavelength of light. Here we show that achromatic optical cloaking in visible spectrum is possible with the mere principle based on geometrical optics. In combining a pair of polarising beam splitters and right-angled prisms, rays of light to be obstructed by an object can make a detour to an observer, while unobstructed rays go straight through two polarising beam splitters. What is observed eventually through the device is simply background image as if nothing exists in between.

Flow stabilization with active hydrodynamic cloaks.

Science.gov (United States)

Urzhumov, Yaroslav A; Smith, David R

2012-11-01

We demonstrate that fluid flow cloaking solutions, based on active hydrodynamic metamaterials, exist for two-dimensional flows past a cylinder in a wide range of Reynolds numbers (Re's), up to approximately 200. Within the framework of the classical Brinkman equation for homogenized porous flow, we demonstrate using two different methods that such cloaked flows can be dynamically stable for Re's in the range of 5-119. The first highly efficient method is based on a linearization of the Brinkman-Navier-Stokes equation and finding the eigenfrequencies of the least stable eigenperturbations; the second method is a direct numerical integration in the time domain. We show that, by suppressing the von Kármán vortex street in the weakly turbulent wake, porous flow cloaks can raise the critical Reynolds number up to about 120 or five times greater than for a bare uncloaked cylinder.

Spherical cloaking using nonlinear transformations for improved segmentation into concentric isotropic coatings.

Science.gov (United States)

Qiu, Cheng-Wei; Hu, Li; Zhang, Baile; Wu, Bae-Ian; Johnson, Steven G; Joannopoulos, John D

2009-08-03

Two novel classes of spherical invisibility cloaks based on nonlinear transformation have been studied. The cloaking characteristics are presented by segmenting the nonlinear transformation based spherical cloak into concentric isotropic homogeneous coatings. Detailed investigations of the optimal discretization (e.g., thickness control of each layer, nonlinear factor, etc.) are presented for both linear and nonlinear spherical cloaks and their effects on invisibility performance are also discussed. The cloaking properties and our choice of optimal segmentation are verified by the numerical simulation of not only near-field electric-field distribution but also the far-field radar cross section (RCS).

The impact of ergonomics intervention on trunk posture and cumulative compression load among carpet weavers.

Science.gov (United States)

Afshari, Davood; Motamedzade, Majid; Salehi, Reza; Soltanian, Alir Raze

2015-01-01

Work-related musculoskeletal disorders of back among weavers are prevalent. Epidemiological studies have shown an association between poor working postures and back disorders among carpet weavers. Therefore, the present study aimed to evaluate the impact of the traditional (A) and ergonomically designed (B) workstations on trunk posture and cumulative compression load in carpet weavers. In this study, subtasks were identified in terms of stressful postures and carpet weaving process. Postural data were collected during knotting and compacting subtasks using inclinometer during four hours for each workstation. Postural data, weight and height of the weavers were entered into the University of Michigan three-dimensional static biomechanical model for estimation of the compression load and cumulative load were estimated from the resultant load and exposure time. Thirteen healthy carpet weavers (four males and nine females) participated in the study. Median trunk flexion angle was reduced with workstation B during knotting subtask (18° versus 8.5°, pergonomically designed workstation.

Protecting Superconducting HTS-Antennas by Meta-Material Cloaks

Science.gov (United States)

2014-04-30

to the cloak are not quantified. Thus, one can only visually judge the performance of the cloaking ability of the structure. In this project, a...materials composed of only s-shaped resonators,” Phys. Rev. E, vol. 70, p. 057605, Nov 2004. 8, 9 [25] J. Pendry, A. Holden, D. Robbins , and W

Indian Carpet Industry after Trade Liberalization. Problems and Prospects

Directory of Open Access Journals (Sweden)

M. Rashid Malik, Rekha Prasad

2015-09-01

Full Text Available This paper aims to examine the constraints and opportunities emerged for the Micro, small and medium enterprises in carpet industry after trade liberalization. The survey method was selected for this study. A structured questionnaire, containing both close and open ended questions was used for data collection. 65 carpet firms of Bhadohi District of Uttar Pradesh registered with All India Carpet Manufacture Association (AICMA were surveyed. Liberalization has brought many opportunities for carpet industry apart from challenges. Findings of the present study show that liberalization gave access to new markets and increased demand of products. Increased cost of raw material, difficulty in ‘export facilitation’ and ‘legal-regulatory framework and difficulty in procuring funds from local financial institutions were identified as the major constraints for the carpet industry.

A 3D tunable and multi-frequency graphene plasmonic cloak

KAUST Repository

Farhat, Mohamed; Rockstuhl, Carsten; Bagci, Hakan

2013-01-01

We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers

Lossless acoustic half-bipolar cylindrical cloak with negative-index metamaterial

Science.gov (United States)

Lee, Yong Y.; Ahn, Doyeol

2018-05-01

A lossless acoustic half-bipolar cylindrical cloak that has an exposed bottom is considered. Here, we show that a cloak that includes a complementary region including a negative-index medium inside of the cloaking shell works in the illumination direction independently even in the presence of the exposed bottom of the structure. This is due to the fact that the phase velocity of the wave in the normal direction can be cancelled in the presence of a boundary containing a negative-index medium that reduces scattering significantly.

Information Concerning Preparation of Specifications for Carpeting.

Science.gov (United States)

Gilliland, John W.

This paper argues for detailed, written carpeting specifications to assure that schools obtain quality products at competitive prices. The advantages of and specifications for school carpeting are given. A sample written specification contains items on: scope, general features, materials, acoustic characteristics, identification and acoustic…

Cloaked Facebook pages: Exploring fake Islamist propaganda in social media

DEFF Research Database (Denmark)

Farkas, Johan Dam; Schou, Jannick; Neumayer, Christina

2017-01-01

This research analyses cloaked Facebook pages that are created to spread political propaganda by cloaking a user profile and imitating the identity of a political opponent in order to spark hateful and aggressive reactions. This inquiry is pursued through a multi-sited online ethnographic case...... study of Danish Facebook pages disguised as radical Islamist pages, which provoked racist and anti-Muslim reactions as well as negative sentiments towards refugees and immigrants in Denmark in general. Drawing on Jessie Daniels’ critical insights into cloaked websites, this research furthermore analyses...

Experimental verification of free-space singular boundary conditions in an invisibility cloak

International Nuclear Information System (INIS)

Wu, Qiannan; Gao, Fei; Song, Zhengyong; Lin, Xiao; Zhang, Youming; Zhang, Baile; Chen, Huanyang

2016-01-01

A major issue in invisibility cloaking, which caused intense mathematical discussions in the past few years but still remains physically elusive, is the plausible singular boundary conditions associated with the singular metamaterials at the inner boundary of an invisibility cloak. The perfect cloaking phenomenon, as originally proposed by Pendry et al for electromagnetic waves, cannot be treated as physical before a realistic inner boundary of a cloak is demonstrated. Although a recent demonstration has been done in a waveguide environment, the exotic singular boundary conditions should apply to a general environment as in free space. Here we fabricate a metamaterial surface that exhibits the singular boundary conditions and demonstrate its performance in free space. Particularly, the phase information of waves reflected from this metamaterial surface is explicitly measured, confirming the singular responses of boundary conditions for an invisibility cloak. (paper)

Experimental verification of free-space singular boundary conditions in an invisibility cloak

Science.gov (United States)

Wu, Qiannan; Gao, Fei; Song, Zhengyong; Lin, Xiao; Zhang, Youming; Chen, Huanyang; Zhang, Baile

2016-04-01

A major issue in invisibility cloaking, which caused intense mathematical discussions in the past few years but still remains physically elusive, is the plausible singular boundary conditions associated with the singular metamaterials at the inner boundary of an invisibility cloak. The perfect cloaking phenomenon, as originally proposed by Pendry et al for electromagnetic waves, cannot be treated as physical before a realistic inner boundary of a cloak is demonstrated. Although a recent demonstration has been done in a waveguide environment, the exotic singular boundary conditions should apply to a general environment as in free space. Here we fabricate a metamaterial surface that exhibits the singular boundary conditions and demonstrate its performance in free space. Particularly, the phase information of waves reflected from this metamaterial surface is explicitly measured, confirming the singular responses of boundary conditions for an invisibility cloak.

Transformation of the corner: A shield cloak and a planar retro-reflector

Science.gov (United States)

Yang, R.; Lei, Z. Y.; Fan, J.; Gao, D. X.; Wang, Z. X.; Xie, Y. J.

2013-10-01

A metallic sheet, coated with a few blocks of all-dielectric isotropic materials, is presented for creating an illusion or an image of a corner based on quasi-conformal transformation optics. On the one hand, our design is able to generate cloaking effects to conceal objects hiding inside a corner. On the other hand, we propose to use such a planar transformation device to represent a corner reflector that reflects light directly back to its source. The full wave simulation shows our device is capable of operating considerably well in a broad frequency range, and presents only the appearance of a bare corner functioning as a shield cloak or a planar retro-reflector.

A cloaking device for transiting planets

Science.gov (United States)

Kipping, David M.; Teachey, Alex

2016-06-01

The transit method is presently the most successful planet discovery and characterization tool at our disposal. Other advanced civilizations would surely be aware of this technique and appreciate that their home planet's existence and habitability is essentially broadcast to all stars lying along their ecliptic plane. We suggest that advanced civilizations could cloak their presence, or deliberately broadcast it, through controlled laser emission. Such emission could distort the apparent shape of their transit light curves with relatively little energy, due to the collimated beam and relatively infrequent nature of transits. We estimate that humanity could cloak the Earth from Kepler-like broad-band surveys using an optical monochromatic laser array emitting a peak power of ˜30 MW for ˜10 hours per year. A chromatic cloak, effective at all wavelengths, is more challenging requiring a large array of tunable lasers with a total power of ˜250 MW. Alternatively, a civilization could cloak only the atmospheric signatures associated with biological activity on their world, such as oxygen, which is achievable with a peak laser power of just ˜160 kW per transit. Finally, we suggest that the time of transit for optical Search for Extraterrestrial Intelligence (SETI) is analogous to the water-hole in radio SETI, providing a clear window in which observers may expect to communicate. Accordingly, we propose that a civilization may deliberately broadcast their technological capabilities by distorting their transit to an artificial shape, which serves as both a SETI beacon and a medium for data transmission. Such signatures could be readily searched in the archival data of transit surveys.

Do Carpets Impair Indoor Air Quality and Cause Adverse Health Outcomes: A Review.

Science.gov (United States)

Becher, Rune; Øvrevik, Johan; Schwarze, Per E; Nilsen, Steinar; Hongslo, Jan K; Bakke, Jan Vilhelm

2018-01-23

Several earlier studies have shown the presence of more dust and allergens in carpets compared with non-carpeted floors. At the same time, adverse effects of carpeted floors on perceived indoor air quality as well as worsening of symptoms in individuals with asthma and allergies were reported. Avoiding extensive carpet use in offices, schools, kindergartens and bedrooms has therefore been recommended by several health authorities. More recently, carpet producers have argued that former assessments were obsolete and that modern rugs are unproblematic, even for those with asthma and allergies. To investigate whether the recommendation to be cautious with the use of carpets is still valid, or whether there are new data supporting that carpet flooring do not present a problem for indoor air quality and health, we have reviewed the literature on this matter. We have not found updated peer reviewed evidence that carpeted floor is unproblematic for the indoor environment. On the contrary, also more recent data support that carpets may act as a repository for pollutants which may become resuspended upon activity in the carpeted area. Also, the use of carpets is still linked to perception of reduced indoor air quality as well as adverse health effects as previously reported. To our knowledge, there are no publications that report on deposition of pollutants and adverse health outcomes associated with modern rugs. However, due to the three-dimensional structure of carpets, any carpet will to some extent act like a sink. Thus, continued caution should still be exercised when considering the use of wall-to-wall carpeted floors in schools, kindergartens and offices, as well as in children's bedrooms unless special needs indicate that carpets are preferable.

Experimental verification of three-dimensional plasmonic cloaking in free-space

International Nuclear Information System (INIS)

Rainwater, D; Kerkhoff, A; Melin, K; Soric, J C; Moreno, G; Alù, A

2012-01-01

We report the experimental verification of metamaterial cloaking for a 3D object in free space. We apply the plasmonic cloaking technique, based on scattering cancellation, to suppress microwave scattering from a finite-length dielectric cylinder. We verify that scattering suppression is obtained all around the object in the near- and far-field and for different incidence angles, validating our measurements with analytical results and full-wave simulations. Our near-field and far-field measurements confirm that realistic and robust plasmonic metamaterial cloaks may be realized for elongated 3D objects with moderate transverse cross-section at microwave frequencies. (paper)

Invisibility and Cloaking: Origins, Present, and Future Perspectives

Science.gov (United States)

Fleury, Romain; Monticone, Francesco; Alù, Andrea

2015-09-01

The development of metamaterials, i.e., artificially structured materials that interact with waves in unconventional ways, has revolutionized our ability to manipulate the propagation of electromagnetic waves and their interaction with matter. One of the most exciting applications of metamaterial science is related to the possibility of totally suppressing the scattering of an object using an invisibility cloak. Here, we review the available methods to make an object undetectable to electromagnetic waves, and we highlight the outstanding challenges that need to be addressed in order to obtain a fully functional coating capable of suppressing the total scattering of an object. Our outlook discusses how, while passive linear cloaks are fundamentally limited in terms of bandwidth of operation and overall scattering suppression, active and/or nonlinear cloaks hold the promise to overcome, at least partially, some of these limitations.

Do Carpets Impair Indoor Air Quality and Cause Adverse Health Outcomes: A Review

Directory of Open Access Journals (Sweden)

Rune Becher

2018-01-01

Full Text Available Several earlier studies have shown the presence of more dust and allergens in carpets compared with non-carpeted floors. At the same time, adverse effects of carpeted floors on perceived indoor air quality as well as worsening of symptoms in individuals with asthma and allergies were reported. Avoiding extensive carpet use in offices, schools, kindergartens and bedrooms has therefore been recommended by several health authorities. More recently, carpet producers have argued that former assessments were obsolete and that modern rugs are unproblematic, even for those with asthma and allergies. To investigate whether the recommendation to be cautious with the use of carpets is still valid, or whether there are new data supporting that carpet flooring do not present a problem for indoor air quality and health, we have reviewed the literature on this matter. We have not found updated peer reviewed evidence that carpeted floor is unproblematic for the indoor environment. On the contrary, also more recent data support that carpets may act as a repository for pollutants which may become resuspended upon activity in the carpeted area. Also, the use of carpets is still linked to perception of reduced indoor air quality as well as adverse health effects as previously reported. To our knowledge, there are no publications that report on deposition of pollutants and adverse health outcomes associated with modern rugs. However, due to the three-dimensional structure of carpets, any carpet will to some extent act like a sink. Thus, continued caution should still be exercised when considering the use of wall-to-wall carpeted floors in schools, kindergartens and offices, as well as in children’s bedrooms unless special needs indicate that carpets are preferable.

Inactivation of dust mites, dust mite allergen, and mold from carpet.

Science.gov (United States)

Ong, Kee-Hean; Lewis, Roger D; Dixit, Anupma; MacDonald, Maureen; Yang, Mingan; Qian, Zhengmin

2014-01-01

Carpet is known to be a reservoir for biological contaminants, such as dust mites, dust mite allergen, and mold, if it is not kept clean. The accumulation of these contaminants in carpet might trigger allergies or asthma symptoms in both children and adults. The purpose of this study is to compare methods for removal of dust mites, dust mite allergens, and mold from carpet. Carpets were artificially worn to simulate 1 to 2 years of wear in a four-person household. The worn carpets were inoculated together with a common indoor mold (Cladosporium species) and house dust mites and incubated for 6 weeks to allow time for dust mite growth on the carpet. The carpets were randomly assigned to one of the four treatment groups. Available treatment regimens for controlling carpet contaminants were evaluated through a literature review and experimentation. Four moderately low-hazard, nondestructive methods were selected as treatments: vacuuming, steam-vapor, Neem oil (a natural tree extract), and benzalkonium chloride (a quaternary ammonium compound). Steam vapor treatment demonstrated the greatest dust mite population reduction (p 0.05) for both physical and chemical methods. The steam-vapor treatment effectively killed dust mites and denatured dust mite allergen in the laboratory environment.

Open active cloaking and illusion devices for the Laplace equation

International Nuclear Information System (INIS)

Ma, Qian; Yang, Fan; Jin, Tian Yu; Mei, Zhong Lei; Cui, Tie Jun

2016-01-01

We propose open active cloaking and illusion devices for the Laplace equation. Compared with the closed configurations of active cloaking and illusion devices, we focus on improving the distribution schemes for the controlled sources, which do not have to surround the protected object strictly. Instead, the controlled sources can be placed in several small discrete clusters, and produce the desired voltages along the controlled boundary, to actively hide or disguise the protected object. Numerical simulations are performed with satisfactory results, which are further validated by experimental measurements. The open cloaking and illusion devices have many advantages over the closed configurations in various potential applications. (paper)

Full control and manipulation of heat signatures: cloaking, camouflage and thermal metamaterials.

Science.gov (United States)

Han, Tiancheng; Bai, Xue; Thong, John T L; Li, Baowen; Qiu, Cheng-Wei

2014-03-19

Thermal camouflage and cloaking can transform an actual heat signature into a pre-controlled one. A viable recipe for controlling and manipulating heat signatures using thermal metamaterials to empower cloaking and camouflage in heat conduction is demonstrated. The thermal signature of the object is thus metamorphosed and perceived as multiple targets with different geometries and compositions, with the original object cloaked. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of fiber material on ozone removal and carbonyl production from carpets

Science.gov (United States)

Abbass, Omed A.; Sailor, David J.; Gall, Elliott T.

2017-01-01

Indoor air quality is affected by indoor materials such as carpets that may act as sources and/or sinks of gas-phase air pollutants. Heterogeneous reactions of ozone with carpets may result in potentially harmful products. In this study, indoor residential carpets of varying fiber types were tested to evaluate their ability to remove ozone, and to assess their role in the production of carbonyls when exposed to elevated levels of ozone. Tests were conducted with six types of new unused carpets. Two sets of experiments were conducted, the first measured ozone removal and ozone deposition velocities, and the second measured primary carbonyl production and secondary production as a result of exposure to ozone. The tests were conducted using glass chambers with volume of 52 L each. Air exchange rates for all tests were 3 h-1. The ozone removal tests show that, for the conditions tested, the polyester carpet sample had the lowest ozone removal (40%), while wool carpet had the greatest ozone removal (65%). Most carpet samples showed higher secondary than primary carbonyl emissions, with carpets containing polypropylene fibers being a notable exception. Carpets with polyester fibers had both the highest primary and secondary emissions of formaldehyde among all samples tested. While it is difficult to make blanket conclusions about the relative air quality merits of various carpet fiber options, it is clear that ozone removal percentages and emissions of volatile organic compounds can vary drastically as a function of fiber type.

Research and development of ion surfing RF carpets for the cyclotron gas stopper at the NSCL

Energy Technology Data Exchange (ETDEWEB)

Gehring, A.E. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87544 (United States); Brodeur, M. [University of Notre Dame, Notre Dame, IN (United States); Bollen, G.; Morrissey, D.J.; Schwarz, S. [National Superconducting Cyclotron Laboratory, Michigan State University, 640 S. Shaw Lane, East Lansing, MI 48824 (United States)

2016-06-01

A model device to transport thermal ions in the cyclotron gas stopper, a next-generation beam thermalization device under construction at the National Superconducting Cyclotron Laboratory, is presented. Radioactive ions produced by projectile fragmentation will come to rest at distances as large as 45 cm from the extraction orifice of the cyclotron gas stopper. The thermalized ions will be transported to the exit by RF carpets employing the recently developed “ion surfing” method. A quarter-circle prototype RF carpet was tested with potassium ions, and ion transport velocities as high as 60 m/s were observed over distances greater than 10 cm at a helium buffer gas pressure of 80 mbar. The transport of rubidium ions from an RF carpet to an electrode below was also demonstrated. The results of this study formed the basis of the design of the RF carpets for use in the cyclotron gas stopper.

Talbot Carpet Simulation for X-ray grating interferometer

Energy Technology Data Exchange (ETDEWEB)

Kim, Youngju; Oh, Ohsung; Jeong, Hanseong; Kim, Jeongho; Lee, Seung Wook [Pusan National University, Busan (Korea, Republic of); Kim, Jongyul; Moon, Myungkook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

In this study, Talbot carpet simulator has been developed to visualize the X-ray grating interference patterns in grating interferometer. We have simulated X-ray interference for a variety of simulations and demonstrated a few examples in this summary. Grating interferometer produces interference of X-ray called Talbot pattern with gratings manufactured in micro scale. Talbot pattern is self-images of phase grating which develops interference as beam splitter that is one of gratings consisted of interferometer. As the other gratings, there are source grating makes coherence and analyze grating is used to analyze interference onto detector. Talbot carpet has been studied as the beam behavior which is distinguished with common X-ray imaging systems. It is helpful to understand grating interferometer and possible to expect beams' oscillation for designing theoretically. We confirm pattern has periodicity produced by interference after pi and pi/2 phase grating and changes in the perpendicular direction to entrance face according to phase objects.

Transmutation of planar media singularities in a conformal cloak.

Science.gov (United States)

Liu, Yichao; Mukhtar, Musawwadah; Ma, Yungui; Ong, C K

2013-11-01

Invisibility cloaking based on optical transformation involves materials singularity at the branch cut points. Many interesting optical devices, such as the Eaton lens, also require planar media index singularities in their implementation. We show a method to transmute two singularities simultaneously into harmless topological defects formed by anisotropic permittivity and permeability tensors. Numerical simulation is performed to verify the functionality of the transmuted conformal cloak consisting of two kissing Maxwell fish eyes.

Experimental Verification of Plasmonic Cloaking at Microwave Frequencies with Metamaterials

International Nuclear Information System (INIS)

Edwards, Brian; Engheta, Nader; Alu, Andrea; Silveirinha, Mario G.

2009-01-01

Plasmonic cloaking is a scattering-cancellation technique based on the local negative polarizability of metamaterials. Here we report its first experimental realization and measurement at microwave frequencies. An array of metallic fins embedded in a high-permittivity fluid has been used to create a metamaterial plasmonic shell capable of cloaking a dielectric cylinder, yielding over 75% reduction of total scattering width.

Size validity of plasma-metamaterial cloaking monitored by scattering wave in finite-difference time-domain method

Directory of Open Access Journals (Sweden)

Alexandre Bambina

2018-01-01

Full Text Available Limitation of the cloak-size reduction is investigated numerically by a finite-difference time-domain (FDTD method. A metallic pole that imitates an antenna is cloaked with an anisotropic and parameter-gradient medium against electromagnetic-wave propagation in microwave range. The cloaking structure is a metamaterial submerged in a plasma confined in a vacuum chamber made of glass. The smooth-permittivity plasma can be compressed in the radial direction, which enables us to decrease the size of the cloak. Theoretical analysis is performed numerically by comparing scattering waves in various cases; there exists a high reduction of the scattering wave when the radius of the cloak is larger than a quarter of one wavelength. This result indicates that the required size of the cloaking layer is more than an object scale in the Rayleigh scattering regime.

Metasurface Cloak Performance Near-by Multiple Line Sources and PEC Cylindrical Objects

DEFF Research Database (Denmark)

Arslanagic, Samel; Yatman, William H.; Pehrson, Signe

2014-01-01

The performance/robustness of metasurface cloaks to a complex field environment which may represent a realistic scenario of radiating sources is presently reported. Attention is devoted to the cloak operation near-by multiple line sources and multiple perfectly electrically conducting cylinders. ...

Realization of a thermal cloak-concentrator using a metamaterial transformer.

Science.gov (United States)

Liu, Ding-Peng; Chen, Po-Jung; Huang, Hsin-Haou

2018-02-06

By combining rotating squares with auxetic properties, we developed a metamaterial transformer capable of realizing metamaterials with tunable functionalities. We investigated the use of a metamaterial transformer-based thermal cloak-concentrator that can change from a cloak to a concentrator when the device configuration is transformed. We established that the proposed dual-functional metamaterial can either thermally protect a region (cloak) or focus heat flux in a small region (concentrator). The dual functionality was verified by finite element simulations and validated by experiments with a specimen composed of copper, epoxy, and rotating squares. This work provides an effective and efficient method for controlling the gradient of heat, in addition to providing a reference for other thermal metamaterials to possess such controllable functionalities by adapting the concept of a metamaterial transformer.

Cloaks and antiobject-independent illusion optics based on illusion media

Science.gov (United States)

Li, Zhou; Zang, XiaoFei; Cai, Bin; Shi, Cheng; Zhu, YiMing

2013-11-01

Based on the transformation optics, we propose a new strategy of illusion media consisting of homogeneous and anisotropic materials. By utilizing the illusion media, invisible cloak is theoretically realized, in which objects covered with the illusion media could not be detected. The cloak here allows neither the propagation of light around the concealed region nor compensates the scattering field of object outside the media. What the cloak does is to shift the region into another place where outside the trace of light, so that objects in that region can disappear. Another application of the illusion media is to create the antiobject-independent illusion optics which means that two objects appear to be like some other objects of our choice. Finite element simulations for two-dimensional cases have been performed to prove these ideas.

All-dielectric invisibility cloaks made of BaTiO3-loaded polyurethane foam

International Nuclear Information System (INIS)

Bao Di; Rajab, Khalid Z; Hao Yang; Kallos, Efthymios; Tang, Wenxuan; Argyropoulos, Christos; Piao Yongzhe; Yang Shoufeng

2011-01-01

Transformation optics has led the way in the development of electromagnetic invisibility cloaks from science fiction to engineering practice. Invisibility cloaks have been demonstrated over a wide range of the electromagnetic spectrum, and with a variety of different fabrication techniques. However, all previous schemes have relied on the use of metamaterials consisting of arrays of sub-wavelength inclusions. We report on the first cloaking structure made of a high-κ dielectric-loaded foam mixture. A polyurethane foam mixed with different ratios of barium titanate is used to produce the required range of permittivities, and the invisibility cloak is demonstrated to work for all incident angles over a wide range of microwave frequencies. This method will greatly facilitate the development and large-scale manufacture of a wide range of transformation optics-based structures. (paper)

Cloaking of 2D particle geometries in a surface medium

Energy Technology Data Exchange (ETDEWEB)

Alexopoulos, A., E-mail: Aris.Alexopoulos@dsto.defence.gov.au [Electronic Warfare and Radar Division, Defence Science and Technology Organisation (DSTO), PO Box 1500, Edinburgh 5111 (Australia); Yau, K.S.B. [Electronic Warfare and Radar Division, Defence Science and Technology Organisation (DSTO), PO Box 1500, Edinburgh 5111 (Australia)

2013-06-17

We theoretically examine the cloaking condition for two-dimensional particles with varying geometry embedded inside a surface medium. General solutions are obtained for multi-layer particle configurations with either all positive or partially negative constitutive parameters respectively. Cloaking of particle geometries that are large relative to the incident wavelength is demonstrated. Theoretical predictions are compared to full-wave numerical simulations for arrays of particles consisting of different geometries.

Use of e-Commerce in Carpet Industry

OpenAIRE

M. Rashid Malik; Rekha Prasad

2014-01-01

This research study is motivated by the growing use of e-commerce in Indian Industries. ECommerce encompasses all business conducted by the use of Information and communication technology. Many business houses have started implementing the use of e-commerce solutions to conduct their businesses. But carpet industry is lagging behind in the use of this very critical tool as we found in our study only 18% carpet exporters are using e-commerce solutions to sell their products across the borders....

Compressibility and resiliency properties of wilton type woven carpets produced with different fiber blend ratio

Science.gov (United States)

Osman, B.; Esin, S.; Sıdıka Ziba, O.

2017-10-01

Carpet is a textile structure that composed of three components: warp (stuffer and chain warp), weft and pile yarns. These textile products are used for areas which will stand up to the use of home, hotel, work place etc. Furthermore, the capable of carpets are related to it’s especially pile performance during use in various areas. During usage, carpets made from various type of raw materials of pile yarn also acts differently that these differentiate determines carpet performance, as well.This study was focused on the compression and resilience behaviour of carpet composed of 100% viscose and 100% acrylic pile yarns and blended pile yarns of blend ratios, 80%/20%, 50%/50% and 20%/80% viscose/acrylic. During the yarn production process, all spinning conditions were kept constant in order to eliminate the yarn production parameters. Five different types of wilton face to face carpet samples were produced from these yarns at the same pile height and pile density on Van de Wiele carpet weaving machine at 110 picks/min machine speed and 1/1 V carpet construction. Compressibility properties of carpets were examined whether blend ratio was statistically significant on carpet resilience or not. The behaviour of pile yarns under pressure is important that leads to understand the growth characteristic which is exposed to decrease and increase loadings during usage of carpet made from these yarns. Results indicated that blend ratio of pile yarns have significance effect on compression behaviour of carpet samples.

Integration of value stream map and strategic layout planning into DMAIC approach to improve carpeting process

Energy Technology Data Exchange (ETDEWEB)

Nagi, A.; Altarazi, S.

2017-07-01

This paper presents an implementation of the Six Sigma DMAIC approach implementing lean tools and facilities layout techniques to reduce the occurrence of different types of nonconformities in the carpeting process. Such carpeting process can be found in several industries such as construction, aviation, and automotive. Design/methodology/approach: The improvement process was built through a sequential implementation of appropriate interconnected tools at each phase of the DMAIC approach. Utilized tools included: Pareto analysis, control charts, Ishikawa chart, 5-whys, failure mode and effect analysis, process capability ratio, value stream mapping, and strategic layout planning. Findings: The carpeting process capability, quality of the product, customer satisfaction, and cost of poor quality were significantly improved. Explicitly, the sigma level was improved from 2.297 to 2.886 and the defects per million opportunities (DPMO) was reduced from 21615 to 3905. Originality/value: This paper has approved the capability of the Six Sigma DMAIC approach to analyze, investigate, and remove the root causes of the carpeting (preparation-installation) process nonconformities.

Integration of value stream map and strategic layout planning into DMAIC approach to improve carpeting process

Directory of Open Access Journals (Sweden)

Ayman Nagi

2017-04-01

Full Text Available Purpose: This paper presents an implementation of the Six Sigma DMAIC approach implementing lean tools and facilities layout techniques to reduce the occurrence of different types of nonconformities in the carpeting process. Such carpeting process can be found in several industries such as construction, aviation, and automotive. Design/methodology/approach: The improvement process was built through a sequential implementation of appropriate interconnected tools at each phase of the DMAIC approach. Utilized tools included: Pareto analysis, control charts, Ishikawa chart, 5-whys, failure mode and effect analysis, process capability ratio, value stream mapping, and strategic layout planning. Findings: The carpeting process capability, quality of the product, customer satisfaction, and cost of poor quality were significantly improved. Explicitly, the sigma level was improved from 2.297 to 2.886 and the defects per million opportunities (DPMO was reduced from 21615 to 3905. Originality/value: This paper has approved the capability of the Six Sigma DMAIC approach to analyze, investigate, and remove the root causes of the carpeting (preparation-installation process nonconformities .

Integration of value stream map and strategic layout planning into DMAIC approach to improve carpeting process

International Nuclear Information System (INIS)

Nagi, A.; Altarazi, S.

2017-01-01

This paper presents an implementation of the Six Sigma DMAIC approach implementing lean tools and facilities layout techniques to reduce the occurrence of different types of nonconformities in the carpeting process. Such carpeting process can be found in several industries such as construction, aviation, and automotive. Design/methodology/approach: The improvement process was built through a sequential implementation of appropriate interconnected tools at each phase of the DMAIC approach. Utilized tools included: Pareto analysis, control charts, Ishikawa chart, 5-whys, failure mode and effect analysis, process capability ratio, value stream mapping, and strategic layout planning. Findings: The carpeting process capability, quality of the product, customer satisfaction, and cost of poor quality were significantly improved. Explicitly, the sigma level was improved from 2.297 to 2.886 and the defects per million opportunities (DPMO) was reduced from 21615 to 3905. Originality/value: This paper has approved the capability of the Six Sigma DMAIC approach to analyze, investigate, and remove the root causes of the carpeting (preparation-installation) process nonconformities.

Fungi in carpeting and furniture dust.

Science.gov (United States)

Schober, G

1991-11-01

The qualitative and quantitative species composition of fungi in carpets and upholstered furniture dust found in the living-rooms of nine Dutch dwellings was examined in a pilot study. Numbers of spores of xerophilic fungi did not differ in dust removed from carpeting and upholstery. Spores of hydrophilic species were found to be more predominant on floors (P less than 0.05), whereas meso-hygrophilic spores, largely dominated by allergologically relevant Penicillium species, were significantly more abundant in dust taken from regularly used furniture (P less than 0.05). Our results indicate that growth conditions for fungi in the micro-habitats of furniture differ from those in carpeting. No statistically significant differences in number of viable spores have been found in samples taken from ground-floor level compared with those taken from 1st to 3rd floor level of dwellings. From this study, the need for a micro-topographic analysis of the fungal flora in the human environment has become apparent. Efficient allergological home sanitation in dwellings of allergic patients requires detailed data about the colonization of the various micro-habitats by allergenic fungi.

A Distance Bounding Protocol for Location-Cloaked Applications.

Science.gov (United States)

Molina-Martínez, Cristián; Galdames, Patricio; Duran-Faundez, Cristian

2018-04-26

Location-based services (LBSs) assume that users are willing to release trustworthy and useful details about their whereabouts. However, many location privacy concerns have arisen. For location privacy protection, several algorithms build a cloaking region to hide a user’s location. However, many applications may not operate adequately on cloaked locations. For example, a traditional distance bounding protocol (DBP)—which is run by two nodes called the prover and the verifier—may conclude an untight and useless distance between these two entities. An LBS (verifier) may use this distance as a metric of usefulness and trustworthiness of the location claimed by the user (prover). However, we show that if a tight distance is desired, traditional DBP can refine a user’s cloaked location and compromise its location privacy. To find a proper balance, we propose a location-privacy-aware DBP protocol. Our solution consists of adding some small delays before submitting any user’s response. We show that several issues arise when a certain delay is chosen, and we propose some solutions. The effectiveness of our techniques in balancing location refinement and utility is demonstrated through simulation.

A Distance Bounding Protocol for Location-Cloaked Applications

Directory of Open Access Journals (Sweden)

Cristián Molina-Martínez

2018-04-01

Full Text Available Location-based services (LBSs assume that users are willing to release trustworthy and useful details about their whereabouts. However, many location privacy concerns have arisen. For location privacy protection, several algorithms build a cloaking region to hide a user’s location. However, many applications may not operate adequately on cloaked locations. For example, a traditional distance bounding protocol (DBP—which is run by two nodes called the prover and the verifier—may conclude an untight and useless distance between these two entities. An LBS (verifier may use this distance as a metric of usefulness and trustworthiness of the location claimed by the user (prover. However, we show that if a tight distance is desired, traditional DBP can refine a user’s cloaked location and compromise its location privacy. To find a proper balance, we propose a location-privacy-aware DBP protocol. Our solution consists of adding some small delays before submitting any user’s response. We show that several issues arise when a certain delay is chosen, and we propose some solutions. The effectiveness of our techniques in balancing location refinement and utility is demonstrated through simulation.

a geometric property of the sierpiński carpet

African Journals Online (AJOL)

The main aim of this paper is to find formulae for the computation of the geodesic metric on the Sierpiński carpet. This is accomplished by introducing carpet coordinates. Subsequently we show the equivalence of the Euclidean and the geodesic metric on this fractal. Mathematics Subject Classification (2000): 28A80, 54E35 ...

Thermal invisibility based on scattering cancellation and mantle cloaking

KAUST Repository

Farhat, Mohamed; Chen, P.-Y.; Bagci, Hakan; Amra, C.; Guenneau, S.; Alù , A.

2015-01-01

We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal invisibility may open new vistas in hiding hot spots in infrared thermography, military furtivity, and electronics heating reduction.

Thermal invisibility based on scattering cancellation and mantle cloaking

KAUST Repository

Farhat, Mohamed

2015-04-30

We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal invisibility may open new vistas in hiding hot spots in infrared thermography, military furtivity, and electronics heating reduction.

Achieving bifunctional cloak via combination of passive and active schemes

Science.gov (United States)

Lan, Chuwen; Bi, Ke; Gao, Zehua; Li, Bo; Zhou, Ji

2016-11-01

In this study, a simple and delicate approach to realizing manipulation of multi-physics field simultaneously through combination of passive and active schemes is proposed. In the design, one physical field is manipulated with passive scheme while the other with active scheme. As a proof of this concept, a bifunctional device is designed and fabricated to behave as electric and thermal invisibility cloak simultaneously. It is found that the experimental results are consistent with the simulated ones well, confirming the feasibility of our method. Furthermore, the proposed method could also be extended to other multi-physics fields, which might lead to potential applications in thermal, electric, and acoustic areas.

Carpet-dust chemicals as measures of exposure: Implications of variability

Directory of Open Access Journals (Sweden)

Whitehead Todd P

2012-03-01

Full Text Available Abstract Background There is increasing interest in using chemicals measured in carpet dust as indicators of chemical exposures. However, investigators have rarely sampled dust repeatedly from the same households and therefore little is known about the variability of chemical levels that exist within and between households in dust samples. Results We analyzed 9 polycyclic aromatic hydrocarbons, 6 polychlorinated biphenyls, and nicotine in 68 carpet-dust samples from 21 households in agricultural communities of Fresno County, California collected from 2003-2005. Chemical concentrations (ng per g dust ranged from Conclusions Our findings suggest that attenuation bias should be relatively modest when using these semi-volatile carpet-dust chemicals as exposure surrogates in epidemiologic studies.

Cost-Benefit and Performance of Handmade Carpets Produced with Wool, Untreated and Chemical Treated Jute Pile Yarns

Science.gov (United States)

Gupta, Shravan Kumar; Goswami, Kamal Kanti

2018-03-01

Jute is a natural fibre which is used to make different type of products due to low cost, easy availability and eco-friendliness. However, the stiffness and harshness of jute fibre affect the use of jute in many products like pile yarns in hand knotted carpets. In this research, a study has been done on the application of jute pile yarns in Persian hand knotted carpet. Three types of commercial yarns (wool, untreated jute and woollenized jute) as well as three types of chemical treated jute yarns (hydrogen peroxide bleached, softened bleached and woollenized yarns) have been applied as pile yarns in Persian hand knotted carpets. Cost-benefit analysis of hand knotted carpets shows that manufacturing cost of wool carpet is lower than others. The contribution of manpower charges is higher than material cost during carpet manufacturing. Hand knotted carpet shows the lowest pile abrasion loss and highest compression recovery when wool is used as pile. Wool hand knotted carpet shows higher compression than untreated and treated jute carpets.

CLASSICAL AREAS OF PHENOMENOLOGY: Material parameter equation for rotating elliptical spherical cloaks

Science.gov (United States)

Ma, Hua; Qu, Shao-Bo; Xu, Zhuo; Zhang, Jie-Qiu; Wang, Jia-Fu

2009-01-01

By using the coordinate transformation method, we have deduced the material parameter equation for rotating elliptical spherical cloaks and carried out simulation as well. The results indicate that the rotating elliptical spherical cloaking shell, which is made of meta-materials whose permittivity and permeability are governed by the equation deduced in this paper, can achieve perfect invisibility by excluding electromagnetic fields from the internal region without disturbing any external field.

Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion

Energy Technology Data Exchange (ETDEWEB)

Stephanie Lucero Konopa; James A. Mulholland; Matthew J. Realff; Paul M. Lemieux [Georgia Institute of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering

2008-08-15

The use of post-consumer carpet as a potential fuel substitute in cement kilns and other high-temperature processes is being considered to address the problem of huge volumes of carpet waste and the opportunity of waste-to-energy recovery. Carpet represents a high volume waste stream, provides high energy value, and contains other recoverable materials for the production of cement. This research studied the emission characteristics of burning 0.46-kg charges of chopped nylon carpet squares, pulverized coal, and particle-board pellets in a pilot-scale natural gas-fired rotary kiln. Carpet was tested with different amounts of water added. Emissions of oxygen, carbon dioxide, nitric oxide (NO), sulfur dioxide (SO{sub 2}), carbon monoxide (CO), and total hydrocarbons and temperatures were continuously monitored. It was found that carpet burned faster and more completely than coal and particle board, with a rapid volatile release that resulted in large and variable transient emission peaks. NO emissions from carpet combustion ranged from 0.06 to 0.15 g/MJ and were inversely related to CO emissions. Carpet combustion yielded higher NO emissions than coal and particleboard combustion, consistent with its higher nitrogen content. S{sub 2} emissions were highest for coal combustion, consistent with its higher sulfur content than carpet or particle board. Adding water to carpet slowed its burn time and reduced variability in the emission transients, reducing the CO peak but increasing NO emissions. Results of this study indicate that carpet waste can be used as an effective alternative fuel, with the caveats that it might be necessary to wet carpet or chop it finely to avoid excessive transient puff emissions due to its high volatility compared with other solid fuels, and that controlled mixing of combustion air might be used to control NO emissions from nylon carpet. 13 refs., 5 figs., 1 tab.

Working Conditions in Carpet Weaving Workshops and Muscu-loskeletal Complaints among Workers in Tabriz - Iran

Directory of Open Access Journals (Sweden)

Jalil Nazari

2012-12-01

Full Text Available Background: Background: Carpet weaving operations usualy involve poor working conditions that can lead to the development of musculoskeletal disorders (MSDs. This study investigated MSDs among car-pet weavers in relation to working conditions from workers' view in Tabriz City, Northwest Iran.Method: This cross-sectional and descriptive study was conducted in city of Tabriz, Iran. Data were col-lected using interviews and questionnaires. The study population consisted of 200 randomly selected healthy weavers from twenty five active carpet weaving workshops.Results: The results showed a high prevalence of musculoskeletal problems among the study population. The most commonly affected body areas were neck, lower back, ankles/feet, hands/wrists, upper back, shoulders and knees, respectively. More than half of the weavers were not satisfied with the thermal con-dition, noise level and cleanliness of the air in the workshops. The result indicated a significant relation-ship between upper back symptoms and daily working time and between lower back symptoms and the numbers of rows of knots woven in a day. Weavers' satisfaction with hand tools shape and thermal condi-tion of the workshops were associated with lower back symptoms, whereas satisfaction with weaving looms were associated with upper back complaints.Conclusion: The poor working condition of hand-woven carpet workshops such as environmental conditionsand work station design and tools should be the subject of ergonomics interventions.

Bacterial amplification and in-place carpet drying: implications for category 1 water intrusion restoration.

Science.gov (United States)

Holland, Jim; Banta, John; Passmore, Boni; Ayers, Mark; Abbott, Sean P; Cole, Eugene C

2012-05-01

The study described in this article investigated whether in-place carpet drying processes resulted in bacterial amplification following water intrusion from a clean water source (category 1) in a residential indoor environment. Bacterial amplification was examined after wetting a 10-year-old carpet and pad that had no history of water intrusion. Three test areas were extracted and dried using industry-recommended procedures for in-place drying and compared to a control area that was not extracted or dried. Results from carpet, pad, and subsurface dust demonstrated that bacterial amplification occurred in all test areas. CFUs of bacteria per gram of carpet surface dust and subsurface dust prior to water intrusion were lower than levels in subsurface dust after in-place drying. The authors' study contributes to information regarding the restoration of water-based carpet damage by professional water damage restoration companies, building maintenance personnel, and housekeeping managers. Results suggest that the appropriate response time for carpet pad salvage is considerably shorter than the current industry recommendation of 72 hours.

TECHNOLOGY OF REPAIRING OPERATIONAL SUITABILITY BITUMEN-RUBEROID CARPET

Directory of Open Access Journals (Sweden)

MISHUK K. M.

2017-01-01

Full Text Available Raising of problem. In the article is presented the analysis of the existing technologies for the restoration of the operational usability of bitumen-polymeric carpet, which allowed to identify their disadvantages, suggested ways to solve problems and highlighted the results of the studies. Firstly, existing bitumen-ruberoid carpet has a residual hydro insulating capacity that can be effectively used. Secondly, the physical condition of the repaired carpet has different types of defects and damage without the proper removal of which is difficult to ensure the desired outcome. The applying of additional layers in conditions of moistening of the lower layers and other defects contributes to their conservation and accelerated loss of operational integrity.Removal of these impacts can be up to 40-50% of all work, can not provide the required effectiveness outcomes in terms of durability, reliability and cost. Therefore the problem is to find ways to achieve a longer after repairing operation with simultaneous reduction of consumables indicators. Purpose of the study is to develop technological solutions serviceability restoration of roofing using unrolling technologies on the principles to minimize the impact of negative factors and the maximum possible use and strengthen the remaining hydro potential of the insulating coating through the use of special impregnating - saturating compositions. Features such compositions are based on the ability to deeply penetrate the thick bitumen-ruberoid carpet and restore his lost components and provide increased water resistance. Conclusion. The article can be introduced in practice of repair-refurbishable works of soft roofing covering of buildings and constructions.

Cloaking and imaging at the same time

Science.gov (United States)

Wu, Qiannan; Xu, Yadong; Li, Hui; Chen, Huanyang

2013-02-01

In this letter, we propose a conceptual device to perform good imaging with positive refraction. At the same time, this device is an isotropic omnidirectional cloak with a perfect electric conductor hiding region and shows versatile illusion optical effects. Numerical simulations are performed to verify the functionalities.

VB Platinum Tile & Carpet, Inc. Information Sheet

Science.gov (United States)

VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

The Pathology of Weaving and Production of the Hand-woven Carpets: Heriz Region Case Study

Directory of Open Access Journals (Sweden)

Sepideh Taravati Mahjoubi

2017-04-01

Full Text Available The carpet, as one of the most precious achievement of people, is a culture. The world’s recognition of Iranian carpet and its glorification originates from endeavor of people who have integrated artistic verve with mysterious attractions of national culture and arts. This study is descriptive-analytic. The data were collected through field research method and direct communication with people and workshops of drawing, weaving, and dyeing. In fact, the assessment tools were taken to the field, and data collection was completed by questioning, interview, observation, and shooting. Then, they were used for derivation, classification, and analysis. SPSS software also used to analyze collected data. . According to the result of this study, regarding the latest forecasts for Iranian hand-woven carpet industry, carpet exports will increase in the future. Therefore, it is better to consider the weaving and marketing of the carpet as a luxury product in order to achieve the profits maintaining the incentive of production in all units involved in the hand-woven carpet’s production and also to reduce poor quality carpets available in the market.

The influence of commercial-grade carpet on postural sway and balance strategy among older adults.

Science.gov (United States)

Dickinson, Joan I; Shroyer, JoAnn L; Elias, Jeffrey W

2002-08-01

The purpose of this research study was to examine the effect of a selected commercial-grade carpet on the static balance of healthy, older adults who had not fallen more than twice in the last 6 months. We tested a total of 45 participants. Each participant stood on a computerized balance machine and was subjected to a carpeted versus a noncarpeted condition while exposed to various sensory limitations. We measured both postural sway and balance strategy. The selected commercial-grade carpet did not affect postural sway. The participants were able to adapt to the sensory limitations regardless of whether they were standing on the carpet. Although balance strategy scores were significantly lower during the carpeted conditions, the clinical significance was questionable as the difference between the means was small for practical purposes. Healthy, older adults did not have difficulty maintaining static balance on the carpeted surface; however, the results could be different if participants who had a history of falling had been included. The results from this study are important and provide a basis of comparison for those individuals who have experienced more than two falls in the last 6 months or who have a history of falling.

Characteristic wave velocities in spherical electromagnetic cloaks

International Nuclear Information System (INIS)

Yaghjian, A D; Maci, S; Martini, E

2009-01-01

We investigate the characteristic wave velocities in spherical electromagnetic cloaks, namely, phase, ray, group and energy-transport velocities. After deriving explicit expressions for the phase and ray velocities (the latter defined as the phase velocity along the direction of the Poynting vector), special attention is given to the determination of group and energy-transport velocities, because a cursory application of conventional formulae for local group and energy-transport velocities can lead to a discrepancy between these velocities if the permittivity and permeability dyadics are not equal over a frequency range about the center frequency. In contrast, a general theorem can be proven from Maxwell's equations that the local group and energy-transport velocities are equal in linear, lossless, frequency dispersive, source-free bianisotropic material. This apparent paradox is explained by showing that the local fields of the spherical cloak uncouple into an E wave and an H wave, each with its own group and energy-transport velocities, and that the group and energy-transport velocities of either the E wave or the H wave are equal and thus satisfy the general theorem.

Asymmetry in Lotto carpets and its implication for Hockney's optical projection theory

Science.gov (United States)

Stork, David G.

2005-03-01

Recently the artist David Hockney theorized that some European painters as early as 1420 used concave mirrors and, later, converging lenses, to project real inverted images onto their canvases or other supports which they then traced and painted over. We consider a specific painting adduced as the primary evidence for this bold theory by Hockney and his collaborator, thin-film physicist Charles Falco: Lorenzo Lotto"s Husband and wife (c. 1543). These projection theorists attribute perspective anomalies in the painting to Lotto repositioning a concave mirror, specifically to overcome its limitations in depth of field. Their analysis lies thoroughly and crucially upon the assumption that the physical carpet pattern was symmetric. We point to a study of "Lotto carpets" surviving in museum collections that shows that these comparison carpets are significantly asymmetric. There seems to be no persuasive independent evidence to support the projection proponents" assumption that these carpets, hand-knotted by children in 16th-century Turkey, were symmetric. Moreover, the angular asymmetries in these surviving carpets are nearly the same as those corresponding to the anomalies in the painting, strongly suggesting that these "anomalies" are in fact due to inherent carpet asymmetries, not to changes in configuration of an optical projector. We show that a non-optical explanation can fit the visual evidence with a precision roughly equal to that of the projection theory, but without the need to invoke a complicated, undocumented optical system. Finally, had Lotto used such an optical projector, we would expect both the general historical documentary record and Lotto"s own writings to indicate as much; however no such corroboratory evidence exists. We conclude by rejecting the numerous claims of "proof" that Lotto used optical projections when executing this painting.

Ulster Carpets - Cleaner Production option report

DEFF Research Database (Denmark)

Wenzel, Henrik; Mercer, David

A survey on options for saving water and energy was conducted at Ulster Carpets on 14th November 2002 by Henrik Wenzel from the Institute for Product Development in Denmark, and David Mercer from Enviros, South Africa. This report details observations made during this site visit and makes...

Destroy The Castle: A 3D Magic Carpet-like Game

OpenAIRE

Ondrčková, Simona

2017-01-01

Title: Destroy the Castle: A 3D Magic Carpet-like Game Author: Simona Ondrčková Department: Department of Distributed and Dependable Systems Supervisor: Mgr. Pavel Ježek, Ph.D., Department of Distributed and Dependable Systems Abstract: The goal of the thesis is to create a computer game based on a game called Magic Carpet. The game has two main interesting aspects from the programming point of view: artificial intelligence and an editor. The artificial intelligence uses different approaches ...

Free-space entangled quantum carpets

Science.gov (United States)

Barros, Mariana R.; Ketterer, Andreas; Farías, Osvaldo Jiménez; Walborn, Stephen P.

2017-04-01

The Talbot effect in quantum physics is known to produce intricate patterns in the probability distribution of a particle, known as "quantum carpets," corresponding to the revival and replication of the initial wave function. Recently, it was shown that one can encode a D -level qudit in such a way that the Talbot effect can be used to process the D -dimensional quantum information [Farías et al., Phys. Rev. A 91, 062328 (2015), 10.1103/PhysRevA.91.062328]. Here we introduce a scheme to produce free-propagating "entangled quantum carpets" with pairs of photons produced by spontaneous parametric down-conversion. First we introduce an optical device that can be used to synthesize arbitrary superposition states of Talbot qudits. Sending spatially entangled photon pairs through a pair of these devices produces an entangled pair of qudits. As an application, we show how the Talbot effect can be used to test a D -dimensional Bell inequality. Numerical simulations show that violation of the Bell inequality depends strongly on the amount of spatial correlation in the initial two-photon state. We briefly discuss how our optical scheme might be adapted to matter wave experiments.

24 CFR 200.948 - Building product standards and certification program for carpet cushion.

Science.gov (United States)

2010-04-01

... Minimum Property Standards § 200.948 Building product standards and certification program for carpet... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Building product standards and certification program for carpet cushion. 200.948 Section 200.948 Housing and Urban Development Regulations...

Devil's carpet of topological entropy and complexity of global dynamical behavior

International Nuclear Information System (INIS)

Cao, K.-F.; Zhang, X.-S.; Zhou Zhong; Peng, S.-L.

2003-01-01

For bimodal maps the concept of an equal topological entropy class (ETEC) is established by the dual star products. All the infinitely many ETEC plateaus and single points are harmonically organized in the kneading parameter plane, they construct a multifractal devil's carpet, which possesses a perfect subregion similarity and a dual central symmetry. The entropy devil's carpet reveals the complexity of global dynamical behavior in the whole parameter plane of bimodal systems

Characteristics Of Virgin And Pulled Wool Fibres Used In Tunisian Handmade Carpets

Directory of Open Access Journals (Sweden)

Taoufik Harizi

2015-08-01

Full Text Available Abstract Many factors such as production methods fibre quality and structural parameters have distinctive influence on the quality and performance of a hand woven carpet. Because the most common fiber used for producing handmade carpet is wool this experiment was aimed to identify virgin and pulled wool characteristics of Tunisian sheep breeds. A total of 84 sheep and 15 samples of commercial pulled wool were used in this study. Samples of fiber were analyzed using standard objective measurements for staple length SL mean fiber diameter MFD coefficient of variation of fiber diameter FDCV fine fiber contain FC Breaking strength and Elongation. Results showed that Tunisian wool can be considered as medium wool. By conducting well-planned sorting Fine Queue of west sheep breed can supply the wool needed for textile industries. The wool of other sheep breeds can be used in handmade carpets. Also staple strength as one of the important wool characteristic affected significantly by alkali treatment during chemical unhairing process compared with wool collected by shearing process. Great attention must be paid to know the real characteristics of pulled wool before using it in handmade carpet industry.

Soil reinforcement with recycled carpet wastes.

Science.gov (United States)

Ghiassian, Hossein; Poorebrahim, Gholamreza; Gray, Donald H

2004-04-01

A root or fibre-reinforced soil behaves as a composite material in which fibres of relatively high tensile strength are embedded in a matrix of relatively plastic soil. Shear stresses in the soil mobilize tensile resistance in the fibres, which in turn impart greater strength to the soil. A research project has been undertaken to study the influence of synthetic fibrous materials for improving the strength characteristics of a fine sandy soil. One of the main objectives of the project is to explore the conversion of fibrous carpet waste into a value-added product for soil reinforcement. Drained triaxial tests were conducted on specimens, which were prepared in a cylindrical mould and compacted at their optimum water contents. The main test variables included the aspect ratio and the weight percentage of the fibrous strips. The results clearly show that fibrous inclusions derived from carpet wastes improve the shear strength of silty sands. A model developed to simulate the effect of the fibrous inclusions accurately predicts the influence of strip content, aspect ratio and confining pressure on the shear strength of reinforced sand.

Evaluation of Related Risk Factors in Number of Musculoskeletal Disorders Among Carpet Weavers in Iran.

Science.gov (United States)

Karimi, Nasim; Moghimbeigi, Abbas; Motamedzade, Majid; Roshanaei, Ghodratollah

2016-12-01

Musculoskeletal disorders (MSDs) are a common problem among carpet weavers. This study was undertaken to introduce affecting personal and occupational factors in developing the number of MSDs among carpet weavers. A cross-sectional study was performed among 862 weavers in seven towns with regard to workhouse location in urban or rural regions. Data were collected by using questionnaires that contain personal, workplace, and information tools and the modified Nordic MSDs questionnaire. Statistical analysis was performed by applying Poisson and negative binomial mixed models using a full Bayesian hierarchical approach. The deviance information criterion was used for comparison between models and model selection. The majority of weavers (72%) were female and carpet weaving was the main job of 85.2% of workers. The negative binomial mixed model with lowest deviance information criterion was selected as the best model. The criteria showed the convergence of chains. Based on 95% Bayesian credible interval, the main job and weaving type variables statistically affected the number of MSDs, but variables age, sex, weaving comb, work experience, and carpet weaving looms were not significant. According to the results of this study, it can be concluded that occupational factors are associated with the number of MSDs developing among carpet weavers. Thus, using standard tools and decreasing hours of work per day can reduce frequency of MSDs among carpet weavers.

Chirality-Assisted Electronic Cloaking of Confined States in Bilayer Graphene

Science.gov (United States)

Gu, Nan; Rudner, Mark; Levitov, Leonid

2011-10-01

We show that the strong coupling of pseudospin orientation and charge carrier motion in bilayer graphene has a drastic effect on transport properties of ballistic p-n-p junctions. Electronic states with zero momentum parallel to the barrier are confined under it for one pseudospin orientation, whereas states with the opposite pseudospin tunnel through the junction totally uninfluenced by the presence of confined states. We demonstrate that the junction acts as a cloak for confined states, making them nearly invisible to electrons in the outer regions over a range of incidence angles. This behavior is manifested in the two-terminal conductance as transmission resonances with non-Lorentzian, singular peak shapes. The response of these phenomena to a weak magnetic field or electric-field-induced interlayer gap can serve as an experimental fingerprint of electronic cloaking.

Ergonomic Interventions in Manual Handling of Carpets to the retail sellers in a textile company

Directory of Open Access Journals (Sweden)

E. Darvishi

2015-04-01

.Conclusion: By implementing ergonomics interventions in carpet delivery sites, the risk factors of MSDs, induced by manual carpet handling, were reduced and safety and ergonomic conditions of the retailers were improved, compared to the previous conditions.

Intersection of the Sierpinski carpet with its rational translate

International Nuclear Information System (INIS)

Dai Meifeng; Tian Lixin

2007-01-01

Motivated by Mandelbrot's idea of referring to lacunarity of Cantor sets in terms of departure from translation invariance, Nekka and Li studied the properties of these translation sets and showed how they can be used for a classification purpose. In this paper, we pursue this study on the Sierpinski carpet with its rational translate. We also get the fractal structure of intersection I(x, y) of the Sierpinski carpet with its translate. We find that the packing measure of these sets forms a discrete spectrum whose non-zero values come only from shifting numbers with a finite triadic expansion. Concretely, when x and y have a finite triadic expansion, a very brief calculation formula of the measure is given

An analogy strategy for transformation optics

International Nuclear Information System (INIS)

Yao, Kan; Liu, Yongmin; Chen, Huanyang; Jiang, Xunya

2014-01-01

We introduce an analogy strategy to design transformation optical devices. Based on the similarities between field lines in different physical systems, the trajectories of light can be intuitively determined to curve in a gentle manner, and the resulting materials are isotropic and nonmagnetic. Furthermore, the physical meaning of the analogue problems plays a key role in the removal of dielectric singularities. We illustrate this approach by creating two designs of carpet cloak and a collimating lens as representative examples in two- and three-dimensional spaces, respectively. The analogy strategy not only reveals the intimate connections between different physical disciplines, such as optics, fluid mechanics and electrostatics, but also provides a heuristic pathway to designing advanced photonic systems

Evaluation of Related Risk Factors in Number of Musculoskeletal Disorders Among Carpet Weavers in Iran

Directory of Open Access Journals (Sweden)

Nasim Karimi

2016-12-01

Conclusion: According to the results of this study, it can be concluded that occupational factors are associated with the number of MSDs developing among carpet weavers. Thus, using standard tools and decreasing hours of work per day can reduce frequency of MSDs among carpet weavers.

An Improved Privacy-Preserving Framework for Location-Based Services Based on Double Cloaking Regions with Supplementary Information Constraints

Directory of Open Access Journals (Sweden)

Li Kuang

2017-01-01

Full Text Available With the rapid development of location-based services in the field of mobile network applications, users enjoy the convenience of location-based services on one side, while being exposed to the risk of disclosure of privacy on the other side. Attacker will make a fierce attack based on the probability of inquiry, map data, point of interest (POI, and other supplementary information. The existing location privacy protection techniques seldom consider the supplementary information held by attackers and usually only generate single cloaking region according to the protected location point, and the query efficiency is relatively low. In this paper, we improve the existing LBSs system framework, in which we generate double cloaking regions by constraining the supplementary information, and then k-anonymous task is achieved by the cooperation of the double cloaking regions; specifically speaking, k dummy points of fixed dummy positions in the double cloaking regions are generated and the LBSs query is then performed. Finally, the effectiveness of the proposed method is verified by the experiments on real datasets.

Exploitation of very small particles to enhance the probative value of carpet fibers.

Science.gov (United States)

Stoney, David A; Neumann, Cedric; Mooney, Kim E; Wyatt, J Matney; Stoney, Paul L

2015-07-01

Environmentally acquired very small particles (VSP), present on the surfaces of carpet fibers, have shown potential for the association of fibers with their carpet source. To unlock this potential, research is required addressing a number of areas, including the application of methods under realistic casework conditions and the utilization of computational methods for the refinement and testing of the approach. In this work field collections of carpet fibers were conducted by crime scene practitioners under realistic casework conditions. VSP were isolated using previously developed methods, and analyses were conducted using SEM/EDS analytical protocols in an operational crime laboratory setting. Computational methods were designed, allowing sets of hundreds to thousands of VSP to be characterized. Classifiers were designed to associate and discriminate among specimens. These classifiers were applied to the VSP data for specimens collected by crime scene practitioners, as well as to a previously collected research dataset. Quantitative measures of correspondence and probative value were designed based on the classification measures and successfully applied to both sets of VSP data. Particle sets larger than 500 showed strong promise for quantitative associations with their sources. The use of larger numbers of target particle types (TPTs) showed strong promise to improve the performance of classification and association. Overall, the usefulness of VSP to provide objective, quantitative associations has been established. Because VSP are acquired post-manufacture, these methods can address fundamental limitations to probative value that arise when class characteristics, determined by manufacture, are shared among mass produced commodities. These findings are of broad significance for the future of trace evidence analysis. The results of this research are likely extendable, with minor modifications, to other trace evidence types (such as glass, tape and human hair

Experimental validation of an ultra-thin metasurface cloak for hiding a metallic obstacle from an antenna radiation at low frequencies

Science.gov (United States)

Teperik, Tatiana V.; Burokur, Shah Nawaz; de Lustrac, André; Sabanowski, Guy; Piau, Gérard-Pascal

2017-07-01

We demonstrate numerically and experimentally an ultra-thin (≈ λ/240) metasurface-based invisibility cloak for low frequency antenna applications. We consider a monopole antenna mounted on a ground plane and a cylindrical metallic obstacle of diameter smaller than the wavelength located in its near-field. To restore the intrinsic radiation patterns of the antenna perturbed by this obstacle, a metasurface cloak consisting simply of a metallic patch printed on a dielectric substrate is wrapped around the obstacle. Using a finite element method based commercial electromagnetic solver, we show that the radiation patterns of the monopole antenna can be restored completely owing to electromagnetic modes of the resonant cavity formed between the patch and obstacle. The metasurface cloak is fabricated, and the concept is experimentally demonstrated at 125 MHz. Performed measurements are in good agreement with numerical simulations, verifying the efficiency of the proposed cloak.

A study on effect of world trade organization on Iran's membership on export of Iranian handmade carpet

Directory of Open Access Journals (Sweden)

Mansoureh Golmeymi

2013-10-01

Full Text Available World Trade Organization (WTO has been established to facilitate fringe trade in the world and there are many studies associated with the effect of WTO membership on export of various countries. This paper presents an empirical investigation to find the effect of WTO membership on export of Iranian handmade carpet. The survey uses insights from 80 experts who have at least ten years of related job experiences in carpet industry by performing an expletory and using descriptive and quantitative method for analyzing the data. The results of the survey indicate that Iran's membership in WTO will most likely reduce the sales price of handmade carpet. In addition, Iran's membership in WTO will increase scientific and professional power in handmade carpet. It will also help industry get more exposure into international market.

Ethnic Minority Entrepreneurs in the International Carpet Trade

DEFF Research Database (Denmark)

Rezaei, Shahamak; Dana, Leo-Paul; Light, Ivan

2013-01-01

The paper discusses the pre-modern bazaar and the authors (Shahamak Rezaei Roskilde University, Ivan Light UCLA, Léo-Paul Dana Groupe Sup de Co Montpellier Business School - Montpellier Research in Management) observe changes in the sector as Persian carpets can now be sourced from new entrants...

Application of Geospatial Information System for the Study of Illuminance in Carpet Weaving Workshops in Bokan, Iran

Directory of Open Access Journals (Sweden)

Faramarz Madjidi

2015-12-01

Full Text Available Background: Carpet weaving is an occupation that requires sufficient and appropriate lighting. The lighting in carpet weaving workshops affects the productivity and the physical and mental health of workers. Therefore, the evaluation of the illumination and the identification of work stations requiring lighting modifications will be helpful in promotion of the health and safety of workers in carpet weaving workshops. Methods: This study was carried out for the evaluation of illumination on the basis of Geospatial Information System (GIS technology in two carpet weaving workshops of Bokan city. As per the norms of Illumination Engineering Society, the sensors of the photometer Testo 545 were placed at lowest and highest of 35 and 163 cm in workshop I, and at 40 and 245 cm in workshop II, which correspond to the lowest and highest work surfaces in the respective workshops. Total, natural, and artificial illuminance was measured in the center of each measurement station using the photometer, and data was analyzed using the Arc GIS software. The maximum and minimum illuminances as well as isolux curves were obtained for each workshop. Results: The illuminance in workshops I and II were found to be lower and higher, respectively, than 200 lux, which is considered the standard for carpet weaving workshops. Thus, improving the artificial lighting system or redesigning it is essential for ensuring that the standard conditions of illuminance (200–300 lux are provided. Discussion: This study showed that the application of GIS technology renders the assessment of illumination in carpet weaving workshops possible. This assessment method could also prove useful for determining the exact stations in the carpet weaving workshops that need modifications, thereby leading to cost reduction.

Assessment of Interior General and Local Lighting in Carpet Weaving Workshops in Bijar City

OpenAIRE

Rostam Golmohamadi; Homeira Alizadeh; Motamedzade Majid; Soltanian Alireza

2014-01-01

Background & Objectives : The comfort lighting in the workplace provides employees visual health which can improve safety, visual comfort and enhance performance and product quality. The present study was conducted to evaluate general and local lighting in carpet weaving workshops in Bijar city . Methods : In this descriptive analytical study, 101 carpet weaving workshops were randomly selected. The illuminance were measured based on the models and formulas presented in Illuminating Engin...

Revival of cloaking effect in a driven bilayer graphene vector barrier

Science.gov (United States)

Maiti, S.; Panigrahi, A.; Biswas, R.; Sinha, C.

2018-05-01

Transmission profiles in bilayer graphene are studied theoretically through a rectangular vector potential (magnetic) barrier with and without the presence of an oscillatory potential. Unlike the electrostatic barrier, the Fano resonances (FR) are noted in the transmission spectra both for normal and glancing incidences due to non-conservation of chirality for a static vector barrier. The results for normal incidence indicate that the cloaking effect is a manifestation of the chirality conservation in charge transport through bilayer graphene scalar barriers. It is also noted that the aforesaid FR for a static vector barrier might disappear (photon induced electronic cloaking effect) due to the predominant photon exchange processes in presence of an external oscillating potential. The study of Fano resonances in transmission spectrum is in high demand in respect of localization of charge carriers in graphene nano structures for its potential applications in digital device fabrications.

Schiffer's Conjecture, Interior Transmission Eigenvalues and Invisibility Cloaking: Singular Problem vs. Nonsingular Problem

OpenAIRE

Liu, Hongyu

2012-01-01

In this note, we present some interesting observations on the Schiffer's conjecture, interior transmission eigenvalue problem and their connections to singular and nonsingular invisibility cloaking problems of acoustic waves.

OzPythonPlex: An optimised forensic STR multiplex assay set for the Australasian carpet python (Morelia spilota).

Science.gov (United States)

Ciavaglia, Sherryn; Linacre, Adrian

2018-05-01

Reptile species, and in particular snakes, are protected by national and international agreements yet are commonly handled illegally. To aid in the enforcement of such legislation, we report on the development of three 11-plex assays from the genome of the carpet python to type 24 loci of tetra-nucleotide and penta-nucleotide repeat motifs (pure, compound and complex included). The loci range in size between 70 and 550 bp. Seventeen of the loci are newly characterised with the inclusion of seven previously developed loci to facilitate cross-comparison with previous carpet python genotyping studies. Assays were optimised in accordance with human forensic profiling kits using one nanogram template DNA. Three loci are included in all three of the multiplex reactions as quality assurance markers, to ensure sample identity and genotyping accuracy is maintained across the three profiling assays. Allelic ladders have been developed for the three assays to ensure consistent and precise allele designation. A DNA reference database of allele frequencies is presented based on 249 samples collected from throughout the species native range. A small number of validation tests are conducted to demonstrate the utility of these multiplex assays. We suggest further appropriate validation tests that should be conducted prior to the application of the multiplex assays in criminal investigations involving carpet pythons. Copyright © 2018 Elsevier B.V. All rights reserved.

Volatility Behaviors of Financial Time Series by Percolation System on Sierpinski Carpet Lattice

Science.gov (United States)

Pei, Anqi; Wang, Jun

2015-01-01

The financial time series is simulated and investigated by the percolation system on the Sierpinski carpet lattice, where percolation is usually employed to describe the behavior of connected clusters in a random graph, and the Sierpinski carpet lattice is a graph which corresponds the fractal — Sierpinski carpet. To study the fluctuation behavior of returns for the financial model and the Shanghai Composite Index, we establish a daily volatility measure — multifractal volatility (MFV) measure to obtain MFV series, which have long-range cross-correlations with squared daily return series. The autoregressive fractionally integrated moving average (ARFIMA) model is used to analyze the MFV series, which performs better when compared to other volatility series. By a comparative study of the multifractality and volatility analysis of the data, the simulation data of the proposed model exhibits very similar behaviors to those of the real stock index, which indicates somewhat rationality of the model to the market application.

Tunable Graphene Metasurface Reflectarray for Cloaking, Illusion, and Focusing

Science.gov (United States)

Biswas, Sudipta Romen; Gutiérrez, Cristian E.; Nemilentsau, Andrei; Lee, In-Ho; Oh, Sang-Hyun; Avouris, Phaedon; Low, Tony

2018-03-01

This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. We present a graphene-based metasurface that can be actively tuned between different regimes of operation, such as anomalous beam steering and focusing, cloaking, and illusion optics, by applying electrostatic gating without modifying the geometry of the metasurface. The metasurface is designed by placing graphene ribbons on a dielectric cavity resonator, where interplay between geometric plasmon resonances in the ribbons and Fabry-Perot resonances in the cavity is used to achieve a 2 π phase shift. As a proof of concept, we demonstrate that the wave front of the field reflected from a triangular bump covered by the metasurface can be tuned by applying electric bias so as to resemble that of a bare plane and of a spherical object. Moreover, reflective focusing and the change of the reflection direction for the above mentioned cases are also shown.

Automatic grading of appearance retention of carpets using intensity and range images

Science.gov (United States)

Orjuela Vargas, Sergio Alejandro; Ortiz-Jaramillo, Benhur; Vansteenkiste, Ewout; Rooms, Filip; De Meulemeester, Simon; de Keyser, Robain; Van Langenhove, Lieva; Philips, Wilfried

2012-04-01

Textiles are mainly used for decoration and protection. In both cases, their original appearance and its retention are important factors for customers. Therefore, evaluation of appearance parameters are critical for quality assurance purposes, during and after manufacturing, to determine the lifetime and/or beauty of textile products. In particular, appearance retention of textile products is commonly certified with grades, which are currently assigned by human experts. However, manufacturers would prefer a more objective system. We present an objective system for grading appearance retention, particularly, for textile floor coverings. Changes in appearance are quantified by using linear regression models on texture features extracted from intensity and range images. Range images are obtained by our own laser scanner, reconstructing the carpet surface using two methods that have been previously presented. We extract texture features using a variant of the local binary pattern technique based on detecting those patterns whose frequencies are related to the appearance retention grades. We test models for eight types of carpets. Results show that the proposed approach describes the degree of wear with a precision within the range allowed to human inspectors by international standards. The methodology followed in this experiment has been designed to be general for evaluating global deviation of texture in other types of textiles, as well as other surface materials.

31 CFR 560.534 - Importation into the United States of, and dealings in, certain foodstuffs and carpets authorized.

Science.gov (United States)

2010-07-01

... Policy § 560.534 Importation into the United States of, and dealings in, certain foodstuffs and carpets... under chapters 2-23 of the Harmonized Tariff Schedule of the United States; (2) Carpets and other... 9706.00.0060 of the Harmonized Tariff Schedule of the United States. (b) United States persons...

Invisibility problem in acoustics, electromagnetism and heat transfer. Inverse design method

Science.gov (United States)

Alekseev, G.; Tokhtina, A.; Soboleva, O.

2017-10-01

Two approaches (direct design and inverse design methods) for solving problems of designing devices providing invisibility of material bodies of detection using different physical fields - electromagnetic, acoustic and static are discussed. The second method is applied for solving problems of designing cloaking devices for the 3D stationary thermal scattering model. Based on this method the design problems under study are reduced to respective control problems. The material parameters (radial and tangential heat conductivities) of the inhomogeneous anisotropic medium filling the thermal cloak and the density of auxiliary heat sources play the role of controls. A unique solvability of direct thermal scattering problem in the Sobolev space is proved and the new estimates of solutions are established. Using these results, the solvability of control problem is proved and the optimality system is derived. Based on analysis of optimality system, the stability estimates of optimal solutions are established and numerical algorithms for solving particular thermal cloaking problem are proposed.

Control of immature stages of the flea Ctenocephalides felis(Bouché in carpets exposed to cats treated with imidacloprid

Directory of Open Access Journals (Sweden)

L.J. Fourie

2000-07-01

Full Text Available Fleas cause allergic dermatitis in cats and dogs and therefore warrant control. It has been demonstrated previously that there is marked inhibition of the development of the immature stages of the cat flea Ctenocephalides felis on fleece blankets exposed to cats treated with imidacloprid. This study reports on the efficacy of imidacloprid in suppressing adult flea emergence in carpet exposed to treated cats. Circular discs of carpet pre-seeded with flea eggs and larvae were exposed to 6 untreated control and 6 topically treated (imidacloprid 10 % m/v cats 1 to 2 days after treatment and subsequently fortnightly for 6 weeks. Exposure times on alternate days were either 1 or 6 hours. Adult flea yield from carpets was determined 35 days after exposure. Differences between flea yield on control carpets and those exposed for 1 hour were significant only for days +1 and +14. For the 6-hour exposure, differences were significant at all times except on Day +43. The ability of imidacloprid to suppress the yield of adult fleas on carpets (6-hour exposure steadily declined from 82 % (Day +2 to 12 %(Day +43. For the 1-hour exposure it varied inconsistently between 0 and 83 % over the 6-week study period.

Horizontal cloaking and vertical reflection by transformation acoustics

Directory of Open Access Journals (Sweden)

Min Kyung Lee

2013-05-01

Full Text Available This investigation shows that if an acoustic metamaterial bounded by an external rectangle and an internal circular cavity is properly engineered by a set of transformation equations that satisfy certain requirements, it can virtually cloak an object against incoming acoustic waves in one direction and make an incoming wave along the orthogonal direction reflected by an object located inside its inner cavity. The specific transformation equations realizing the metamaterial are suggested and an analysis is carried out to investigate the wave phenomena taking place along the cavity boundary.

Role of Magnetic Carpet in Coronal Heating S. R. Verma & Diksha ...

Indian Academy of Sciences (India)

It is likely that different heating mechanisms are at work in the solar corona. ... ity, termed magnetic carpet contributing to solar activity on a short time .... migrates to the boundaries of supergranule cells and moves along them, fragmenting,.

Source amplitudes for active exterior cloaking

International Nuclear Information System (INIS)

Norris, Andrew N; Amirkulova, Feruza A; Parnell, William J

2012-01-01

The active cloak comprises a discrete set of multipole sources that destructively interfere with an incident time harmonic scalar wave to produce zero total field over a finite spatial region. For a given number of sources and their positions in two dimensions it is shown that the multipole amplitudes can be expressed as infinite sums of the coefficients of the incident wave decomposed into regular Bessel functions. The field generated by the active sources vanishes in the infinite region exterior to a set of circles defined by the relative positions of the sources. The results provide a direct solution to the inverse problem of determining the source amplitudes. They also define a broad class of non-radiating discrete sources. (paper)

Hiding the interior region of core-shell nanoparticles with quantum invisible cloaks

Science.gov (United States)

Lee, Jeng Yi; Lee, Ray-Kuang

2014-04-01

Based on the scattering cancellation, we provide a method not only making a nanoparticle nearly invisible, but also hiding its interior region from the outside probing matter wave. By applying the interplay among the nodal points of partial waves along with the concept of streamline in fluid dynamics for probability flux, a quantum invisible cloak to the electron transport in a host semiconductor is demonstrated by simultaneously guiding the probability flux outside a hidden region and keeping the total scattering cross section negligible. As the probability flux vanishes in the interior region, one can embed any materials inside a multiple core-shell nanoparticle without affecting physical observables from the outside. Our results reveal the possibility to design a protection shield layer for fragile interior parts from the impact of transport electrons.

Fluctuation behaviors of financial time series by a stochastic Ising system on a Sierpinski carpet lattice

Science.gov (United States)

Fang, Wen; Wang, Jun

2013-09-01

We develop a financial market model using an Ising spin system on a Sierpinski carpet lattice that breaks the equal status of each spin. To study the fluctuation behavior of the financial model, we present numerical research based on Monte Carlo simulation in conjunction with the statistical analysis and multifractal analysis of the financial time series. We extract the multifractal spectra by selecting various lattice size values of the Sierpinski carpet, and the inverse temperature of the Ising dynamic system. We also investigate the statistical fluctuation behavior, the time-varying volatility clustering, and the multifractality of returns for the indices SSE, SZSE, DJIA, IXIC, S&P500, HSI, N225, and for the simulation data derived from the Ising model on the Sierpinski carpet lattice. A numerical study of the model’s dynamical properties reveals that this financial model reproduces important features of the empirical data.

Efficacy of silver dihydrogen citrate and steam vapor against a human norovirus surrogate, feline calicivirus, in suspension, on glass, and carpet.

Science.gov (United States)

Buckley, David; Dharmasena, Muthu; Fraser, Angela; Pettigrew, Charles; Anderson, Jeffery; Jiang, Xiuping

2018-04-06

Carpets and other soft surfaces have been associated with prolonged and reoccurring human norovirus (HuNoV) outbreaks. Environmental hygiene programs are important to prevent and control HuNoV outbreaks. Despite our knowledge of HuNoV transmission via soft surfaces, no commercially available disinfectants have been evaluated on carpets. Our aim was to adapt a current standardized method for virucidal testing by assessing two disinfection technologies, silver dihydrogen citrate (SDC) and steam vapor, against one HuNoV surrogate, feline calicivirus (FCV), on wool and nylon carpets. First, we evaluated the effect of both technologies on appearance of carpet. Next, we evaluated the efficacy of SDC in suspension and the efficacy of SDC and steam vapor against FCV on a glass surface, each with and without serum. Lastly, we tested both technologies on two types of carpet, wool and nylon. Both carpets exhibited no obvious color changes; however, SDC treatments left a residue while steam vapor left minor abrasions to fibers. SDC in suspension and on glass reduced FCV by 4.65 and >4.66 log 10 pfu, respectively, but demonstrated reduced efficacy in the presence of serum. However, SDC was only efficacious against FCV on nylon (3.62 log 10 pfu reduction) and not wool (1.82 log 10 pfu reduction). Steam vapor reduced FCV by >4.93 log 10 pfu on glass in 10 sec and >3.68 log 10 pfu reduction on wool and nylon carpet carriers in 90 sec. There was limited reduction to FCV RNA under both treatments compared to infectivity assays but RNA reductions were higher in samples that contained serum. IMPORTANCE Human noroviruses (HuNoV) account for ca. 20% of all diarrheal cases worldwide. Disease symptoms may include diarrhea and vomit with both known to contribute to transmission. Prevention and control of HuNoV are difficult because they are environmentally resilient and resistant to many disinfectants. Several field studies have linked both hard and soft surfaces to HuNoV outbreaks

Female carpet weavers' visual acuity and effective factors: Fordu rural area of Qom

Directory of Open Access Journals (Sweden)

Khajenasiri F.

2007-11-01

Full Text Available Background: Healthy vision of workers is one of the important elements in carpet weaving industry which has essential role in improving of the job quality and efficiency. Visual acuity is the primary outcome measure in most studies involving eye diseases. Ihe aim of this study was determination of visual acuity and its effective factors in women carpet weaver in fordu rural area of Qom has been investigated.  Methods: In a cross-sectional (descriptive-analytical study visual acuity of 177 women carpet weaver has been determined. Job hours per day, job history, age, literacy, trauma history, diabetes history, family history of eye diseases, eye diseases history and family size  of subjects were determined .Results: The results of study indicated that the right eyes visual acuity of 72.4 % of women were desirable (0 - 0.8 and 27.6 % were undesirable (0.9-1.2. These results for the left eyes were 69.5 % and 30.5 % respectively. In addition, the result showed that with increasing the job hours and history and age, percent of women with undesirable both eyes visual acuity were increased. With higher literacy levels, percent of women with undesirable both eyes visual acuity decreased. In subjects with truma history, the undesirable visual acuity was higher. In this study the relation between visual acuity and job history, age, literacy, truma history and eye diseases history were statistically significant (in all cases P<0.05.Conclusions: High percentage of women carpet weaver were in undesirable  visual acuity and in this study the relation between visual acuity and job history, age, literacy, trauma history and eye diseases history were statistically significant (in all cases P<0.05.

Active electromagnetic invisibility cloaking and radiation force cancellation

Science.gov (United States)

Mitri, F. G.

2018-03-01

This investigation shows that an active emitting electromagnetic (EM) Dirichlet source (i.e., with axial polarization of the electric field) in a homogeneous non-dissipative/non-absorptive medium placed near a perfectly conducting boundary can render total invisibility (i.e. zero extinction cross-section or efficiency) in addition to a radiation force cancellation on its surface. Based upon the Poynting theorem, the mathematical expression for the extinction, radiation and amplification cross-sections (or efficiencies) are derived using the partial-wave series expansion method in cylindrical coordinates. Moreover, the analysis is extended to compute the self-induced EM radiation force on the active source, resulting from the waves reflected by the boundary. The numerical results predict the generation of a zero extinction efficiency, achieving total invisibility, in addition to a radiation force cancellation which depend on the source size, the distance from the boundary and the associated EM mode order of the active source. Furthermore, an attractive EM pushing force on the active source directed toward the boundary or a repulsive pulling one pointing away from it can arise accordingly. The numerical predictions and computational results find potential applications in the design and development of EM cloaking devices, invisibility and stealth technologies.

A rapid assessment of bonded labour in the carpet industry of Pakistan

OpenAIRE

Mueen Nasir, Zafar

2004-01-01

Based on field work in four provinces of Pakistan. Examines labour arrangements and working conditions in the carpet weaving industry and identifies the main characteristics of employers and workers. Investigates the prevalence of debt bondage in the industry and makes recommendations for action and research.

Spherical and cylindrical particle resonator as a cloak system

Science.gov (United States)

Minin, I. V.; Minin, O. V.; Eremeev, A. I.; Tseplyaev, I. S.

2018-05-01

The concept of dielectric spherical or cylindrical particle in resonant mode as a cloak system is offered. In fundamental modes (modes with the smallest volume correspond to |m| = l, and s = 1) the field is concentrated mostly in the equatorial plane and at the surface of the sphere. Thus under resonance modes, such perturbation due to cuboid particle inserted in the spherical or cylindrical particle has almost no effect on the field forming resonance regardless of the value of internal particle material (defect) as long as this material does not cover the region where resonance takes place.

16 CFR 1631.61 - Hide carpets and rugs-alternative washing procedure.

Science.gov (United States)

2010-01-01

... normally used for that type of carpet or rug in service. (b) On February 10, 1972 (37 FR 3010) the Federal... 2″ in diameter and 9″ long composed of nonabsorbent material such as glass or plastic. (4) Select... remove all excess water and wrap around the operating applicator. (7) Immediately, with light pressure...

16 CFR 1630.61 - Hide carpets and rugs-alternative washing procedure.

Science.gov (United States)

2010-01-01

... normally used for that type of carpet or rug in service. (b) On February 10, 1972 (37 FR 3010) the Federal... 2″ in diameter and 9″ long composed of nonabsorbant material such as glass or plastic. (4) Select... remove all excess water and wrap around the operating applicator. (7) Immediately with light pressure...

Broadband reflected wavefronts manipulation using structured phase gradient metasurfaces

Directory of Open Access Journals (Sweden)

Xiao-Peng Wang

2016-06-01

Full Text Available Acoustic metasurface (AMS is a good candidate to manipulate acoustic waves due to special acoustic performs that cannot be realized by traditional materials. In this paper, we design the AMS by using circular-holed cubic arrays. The advantages of our AMS are easy assemble, subwavelength thickness, and low energy loss for manipulating acoustic waves. According to the generalized Snell’s law, acoustic waves can be manipulated arbitrarily by using AMS with different phase gradients. By selecting suitable hole diameter of circular-holed cube (CHC, some interesting phenomena are demonstrated by our simulations based on finite element method, such as the conversion of incoming waves into surface waves, anomalous reflections (including negative reflection, acoustic focusing lens, and acoustic carpet cloak. Our results can provide a simple approach to design AMSes and use them in wavefront manipulation and manufacturing of acoustic devices.

The Geometry-Induced Superhydrophobic Property of Carpet-like Zinc Films

International Nuclear Information System (INIS)

Liang Li-Xing; Deng Yuan; Wang Yao

2013-01-01

Carpet-like zinc films with unique nanowires are fabricated by using a simple physical evaporation method. The definite morphologies of the films endow the superhydrophobic material with a contact angle of about 157.9°, and by additional modification of CF 3 (CF 2 ) 7 CH 2 CH 2 Si(OCH 3 ) 3 the water adhesive force could be tuned from 58.3 μN to 14.6 μN. In order to analyze the controllable adhesion of superhydrophobic Zn films, we study the microstructure and chemical compositions of the films by x-ray diffraction SEM, TEM, HRTEM and EDAX. Furthermore, a model based on the balance of micro-surface energy is proposed to illustrate the relationship of the geometry and wettability properties of the films. The model provides new insights into how to design-oriented microchannels and micro-protuberance on material surfaces, which is of benefit for controlling their ability of caught-collection in air bubbles and water-pinning collection

Assessment of Interior General and Local Lighting in Carpet Weaving Workshops in Bijar City

Directory of Open Access Journals (Sweden)

Rostam Golmohamadi

2014-10-01

Full Text Available Background & Objectives : The comfort lighting in the workplace provides employees visual health which can improve safety, visual comfort and enhance performance and product quality. The present study was conducted to evaluate general and local lighting in carpet weaving workshops in Bijar city . Methods : In this descriptive analytical study, 101 carpet weaving workshops were randomly selected. The illuminance were measured based on the models and formulas presented in Illuminating Engineering Society (IES using luxmeter model Hagner EC1 in height 76 cm from the ground surface. The local illuminances were measured in horizontal and vertical weaving level. Data were analyzed by SPSS software (version 16. Results : Research findings revealed the average of total and artificial illuminance level were 484.5±458.9 and 80.0±49.9 Lx respectively. Mean total, natural and artificial illuminance 39.6, 57.4 and 100 percent were lower the recommended 300 Lx levels. The average of minimum of local illuminance was less than 500 Lx in all workshops. Conclusion : About 60% of workrooms had the acceptable general illuminance levels in middle day. However, due to the insufficient lighting sources in workshops, the artificial illuminance levels are unsuitable. Therefore, it is necessary to improve general illuminance levels by reform and repair artificial lighting systems or redesign them in carpet weaving workrooms.

RAPID MONITORING BY QPCR FOR PATHOGENIC ASPERGILLUS DURING CARPET REMOVAL FROM A HOSPITAL

Science.gov (United States)

Monitoring for pathogenic Aspergillus species using a rapid, highly sensitive, quantitative polymerase chain reaction technique during carpet removal in a burn unit provided data which allowed the patients to be safely returned to the re-floored area sooner than if only conventi...

Distribution pattern of 137Cs in carpets of the forest-moss Pleurozium schreiberi

International Nuclear Information System (INIS)

Mattsson, S.; Liden, K.

1974-11-01

The accumulation, retention and internal cycling of the fallout radionuclide 137 Cs (physical half-life = 30.2 a) has been studied in forest moss (Pleurozium schreberi) collected in southern Sweden (56.4 deg N, 14.3 deg E) during the period 1961-1973. The highest 137 Cs-concentrations have been found in the green top parts of the living plants. The study shows that a dominating part of the deposited 137 Cs is available for transport from dying to growing parts of the plants. The elimination of 137 Cs from living moss-plants as well as from dead modd during the period 1968-1973 can be characterized by the same mean residence time, (4 +- 1)a. The radionuclide 137 Cs and the naturally occurring stable element potassium show different behaviour in the moss vegetation, so that the 137 Cs/K-ratio is higher by a factor of approximately 2 in the dead parts of the moss than in the living parts. The vertical distribution of 137 Cs in the moss-covered ground has been studied down to a dry-mass depth of about 100 kg m -2 and can theoretically be described by a model which was earlier empirically deduced for lichen-covered ground (Mattsson, 1972). The relative penetration of 137 Cs is around five times higher in the ground covered by moss-carpets than in the ground covered by lichen-carpets. During the period 1969-1973, the total amount of 137 Cs retained in the moss-carpet was found to be 64.2 +- 2.2 nCi m -2 . (author)

Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects

KAUST Repository

Wu, Ying

2013-05-06

In this work, we investigate wave transmission property through a zero index metamaterial (ZIM) waveguide embedded with rectangular dielectric defects. We show that total reflection and total transmission (cloaking) can be achieved by adjusting the geometric sizes and/or permittivities of the defects. Our work provides another possibility of manipulating wave propagation through ZIM in addition to the widely studied dielectric defects with cylindrical geometries.

Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects

KAUST Repository

Wu, Ying; Li, Jichun

2013-01-01

In this work, we investigate wave transmission property through a zero index metamaterial (ZIM) waveguide embedded with rectangular dielectric defects. We show that total reflection and total transmission (cloaking) can be achieved by adjusting the geometric sizes and/or permittivities of the defects. Our work provides another possibility of manipulating wave propagation through ZIM in addition to the widely studied dielectric defects with cylindrical geometries.

An empirical study on the effect of WTO membership on Iranian Handicraft industry: A case study of Persian carpet

Directory of Open Access Journals (Sweden)

Zahra Shirzour Aliabadi

2013-05-01

Full Text Available The world Trade Organization (WTO is one of the few organizations, which could significantly influence on foreign trade and consequently on the economic structure of the countries. There are literally different people in Iran who either encourage or discourage WTO membership. Therefore, it is important to analyze Iran’s WTO membership to empower Iranian handmade carpet in international trades and to help improvement in quality of production. The purpose of this research is to study the effects of Iran’s membership in WTO to empower this industry by performing an empirical survey among 100 experts in this industry. Findings demonstrate that access to WTO plays an important role on increasing production of handmade carpet and developing this industry. In addition, the industry needs to incorporate the recent advances on technology to ensure cost efficient production materials. The industry also needs more creative and innovative ideas due to an increase competition in handmade carpet producers from other countries.

Pre-Cloak Comic Superheroes: Tools for the Empowerment of Children

Directory of Open Access Journals (Sweden)

Chris Fradkin

2016-09-01

Full Text Available This note explores the notion of comic superheroes as tools for the empowerment of children. The author details interventions in Rwanda and Brazil, and their different usages of superheroes. With a focus on the superhero’s pre-cloak stage—the stage prior to their employing superpowers—the author offers glimpses of current work in progress to help therapists empower orphaned children. While this area of research is at an early stage, its potential among health professionals is growing. Thus the comic superhero may be more than celluloid, as health professionals learn to use his superpowers.

PRODUCTION OF AN INSULATION MATERIAL FROM CARPET AND BORON WASTES

OpenAIRE

Yasin ERDOĞAN

2016-01-01

Buildings are large consumers of energy in all countries. In regions with harsh climatic conditions, a substantial share of energy goes to heat and cool buildings. This paper reports an investigation of the insulation materials made from mixing carpet wastes with a solution with added crude colemanite ore, one of boron minerals, and a solution with added colemanite wastes from a barrage. A new building insulation material was produced which is name, Halibor. Optimum mixing ratios were determi...

The Analysis Of Environmental Effects On The Design And Production Of Arts In Use, Based On Principles Of Human Geography (Case Study: Iranian Carpet)

OpenAIRE

Moghanipoor, Majidreza; Marasy, Mohsen

2016-01-01

The main topic of this article is recognition and analysis of influences of "Arts in use", as a human phenomenon (from a geographical viewpoint) and one of physical manifestations of culture ( from the environmental viewpoint). Accordingly, opinions and concepts related to this issue have been analyzed in the field of human geography science by an interdisciplinary approach and a descriptive-analytical methodology. Therefore, an "Iranian carpet" as a centerpiece of these studies d...

Stories with and about wall carpets. An anthropological account on the inhabitation of Ursari Romanian Roma

Directory of Open Access Journals (Sweden)

Andreea Racleş

2014-12-01

Full Text Available The aim of this paper is to discuss the ways in which objects assist us in telling small stories about our positions in relation to our inhabited space, but also in relation to perceived dichotomised categories like us-others, the modern-the outmoded, civilized-backward. Acknowledging that narratives emerge from interactions between people, this paper is an attempt to show that an important role in the emergence of stories is played by interactions between people and objects. The wall carpets hung by Ursari Roma from a north-eastern Romanian town and the stories developed with and about these items constitute the main focus of this analysis. From an anthropological and material culture perspective, wall carpets are discussed as material presences in storytelling events and as objects of experience-centred stories that assist Roma people in negotiating and enacting their identities and belongings. Taking a cue from Georgakopoulou, who argues that narratives count on both discourses and activities (2007, home making practices and domestic activities (such as those related to the maintenance of the wall carpets are essential to this paper, as they enable an understanding of the “performative narrative of daily life” (Langellier 2004. The analysis is based on ethnographic material collected in 2014 in the aforementioned community, while the unit of analysis consists of excerpts from discussions with two Roma families, which became storytelling episodes.

Solar Magnetic Carpet III: Coronal Modelling of Synthetic Magnetograms

Science.gov (United States)

Meyer, K. A.; Mackay, D. H.; van Ballegooijen, A. A.; Parnell, C. E.

2013-09-01

This article is the third in a series working towards the construction of a realistic, evolving, non-linear force-free coronal-field model for the solar magnetic carpet. Here, we present preliminary results of 3D time-dependent simulations of the small-scale coronal field of the magnetic carpet. Four simulations are considered, each with the same evolving photospheric boundary condition: a 48-hour time series of synthetic magnetograms produced from the model of Meyer et al. ( Solar Phys. 272, 29, 2011). Three simulations include a uniform, overlying coronal magnetic field of differing strength, the fourth simulation includes no overlying field. The build-up, storage, and dissipation of magnetic energy within the simulations is studied. In particular, we study their dependence upon the evolution of the photospheric magnetic field and the strength of the overlying coronal field. We also consider where energy is stored and dissipated within the coronal field. The free magnetic energy built up is found to be more than sufficient to power small-scale, transient phenomena such as nanoflares and X-ray bright points, with the bulk of the free energy found to be stored low down, between 0.5 - 0.8 Mm. The energy dissipated is currently found to be too small to account for the heating of the entire quiet-Sun corona. However, the form and location of energy-dissipation regions qualitatively agree with what is observed on small scales on the Sun. Future MHD modelling using the same synthetic magnetograms may lead to a higher energy release.

Graphene Carbon Nanotube Carpets Grown Using Binary Catalysts for High-Performance Lithium-Ion Capacitors.

Science.gov (United States)

Salvatierra, Rodrigo Villegas; Zakhidov, Dante; Sha, Junwei; Kim, Nam Dong; Lee, Seoung-Ki; Raji, Abdul-Rahman O; Zhao, Naiqin; Tour, James M

2017-03-28

Here we show that a versatile binary catalyst solution of Fe 3 O 4 /AlO x nanoparticles enables homogeneous growth of single to few-walled carbon nanotube (CNT) carpets from three-dimensional carbon-based substrates, moving past existing two-dimensional limited growth methods. The binary catalyst is composed of amorphous AlO x nanoclusters over Fe 3 O 4 crystalline nanoparticles, facilitating the creation of seamless junctions between the CNTs and the underlying carbon platform. The resulting graphene-CNT (GCNT) structure is a high-density CNT carpet ohmically connected to the carbon substrate, an important feature for advanced carbon electronics. As a demonstration of the utility of this approach, we use GCNTs as anodes and cathodes in binder-free lithium-ion capacitors, producing stable devices with high-energy densities (∼120 Wh kg -1 ), high-power density capabilities (∼20,500 W kg -1 at 29 Wh kg -1 ), and a large operating voltage window (4.3 to 0.01 V).

Wet felting tradition in Bulgaria. Ornamented woolen wedding carpets

DEFF Research Database (Denmark)

Tsvetkova, Elitsa; Frangova, Krassimira; Peneva, Tereza

2017-01-01

-Bulgarians’ cosmogonic concepts about World and the Universe. They symbolize the union of the divine, human and nature; and wish fertility and harmonic co-existence. In most regions, the decoration of old carpets combines the natural colours of undyed wool. Elements intentionally dyed in other colours are rare before 19...... technique. Special attention is drawn to the carpets’ technological structure, composed of multiple layers distinguished by thickness, function, quality and processing of the wool used. To a body consisting of back, middle and front layers, a decoration layer comprised of single dyed woolen wicks is added...

A Summary--The Economics of Carpeting and Resilient Flooring. An Evaluation and Comparison.

Science.gov (United States)

Parks, George M.

Of use to those concerned with the economics of flooring selection and maintenance, this comparison may prove useful as an estimating guide in the preparation of cost estimates for any flooring area where economics is a factor in the choice of materials. All costs attributed to carpet or resilient flooring have been obtained either by survey or…

Psychosocial Factors and Musculoskeletal Pain Among Rural Hand-woven Carpet Weavers in Iran

Directory of Open Access Journals (Sweden)

Reza Chaman

2015-06-01

Conclusion: In home-based workshops of carpet weaving, psychosocial factors and physical loading were associated with MSP. This finding is consistent with studies conducted among other jobs. Considering the preventive programs, the same amount of attention should be paid to psychosocial risk factors and physical loading. Also, further longitudinal studies are needed to investigate the relationship of psychological factors.

Noise Induced Hearing Loss Among Cotton Textile and Carpet Mill Workers

OpenAIRE

ERTEM, Melikşah

1998-01-01

In industry increased mechanisation results in increased noise levels. Operation of textile machines carries a high risk of hearing loss. In this study the evaluation of textile worker's noise induced hearing loss was reviewed cross sectionally. The hearing of 260 textile workers exposed to noise levels between 85-95 dB(A) in carpet and cotton textile factories was assessed by means of air and bone conductance audiograms obtained. The subjects were grouped into five hearin...

In-plant demonstration of energy optimization in beck dyeing of carpet. Final report, June 1, 1979-January 1, 1980

Energy Technology Data Exchange (ETDEWEB)

Tincher, W.C.

1980-01-01

Several energy-conservative technologies have been successfully combined and transferred to a commercial carpet finishing plant to optimize beck dyeing. The technology of bump-and-run, in which the dyebath temperature was allowed to drift for the last 85% of the hold time instead of being maintained by active steam sparging, reduced the energy consumption by 38% with negligible capital investment required. Merging of dyebath reuse with bump-and-run only marginally increased the energy consumption (to 39%), but substantially lowered the plant's finishing costs further by directly recycling dyes, auxiliary chemicals, and water. Final optimization, which merged a technique whereby the carpet was pulled directly from the hot bath with bump-and-run and dyebath reuse, further improved the economics by drastically reducing water/sewer requirements by 90% and eliminating the holding tank/pumping assembly as a reuse requirement. From a carpet industry viewpoint, the demonstrated modifications have a direct energy conservation potential of 2.4 x 10/sup 5/ barrels of oil equivalent per year assuming the technology is directly transferable to similar atmospheric dyeing processes, e.g., beck dyeing of nylon and polyester fabrics, the potential to the entire textile industry is 2.6 x 10/sup 6/ BOE/year. Economically, total potential savings for the carpet industry on reuse incorporation was $1.2 x 10/sup 7//year, based on a 2.3 cents/lb. savings figure. When the allied fabric industry was included, the national potential was raised to $1.0 x 10/sup 8//year. These figures include cost savings due to materials recycled (water, auxiliary chemicals and dyes) as well as energy conservation.

The environmental impact of the carpet chain in Belgium; De milieu-impact van de Belgische tapijtketen

Energy Technology Data Exchange (ETDEWEB)

Bijleveld, M.N.; Sevenster, M.N.

2010-03-15

Under the Belgian project 'Cooperation in the carpet chain around sustainable use of materials' is a comprehensive LCA study in which insight is obtained on three areas: (1) Impact of various polar materials, (2) Impact of various scenarios of disposal of the entire carpet, and (3) Relative impact of the links in the chain of the entire carpet. The chain is modeled in the LCA software programme SimaPro for which use is made of the Ecoinvent database and existing LCA studies, supplemented with data from literature. For the extraction / production of various polar materials the environmental impacts are identified. For other areas, the climate impact as the cumulative energy demand is a measure of the burden on the environment. [Dutch] In het kader van het Belgische project 'Samenwerking in de tapijtketen rond duurzaam materiaalgebruik' is een globale LCA studie uitgevoerd waarbij inzicht is verkregen op drie gebieden: (1) Impact van verscheidene poolmaterialen; (2) Impact van verscheidene scenario's van afvalverwerking van het volledige tapijt; en (3) Relatieve impact van de schakels in de keten van het volledige tapijt. De keten is gemodelleerd in het LCA softwareprogramma Simapro, waarbij gebruik is gemaakt van de EcoInvent database en bestaande LCA-studies, aangevuld met data uit literatuur. Voor de winning/productie van poolmaterialen zijn verscheidene milieu-effecten in kaart gebracht; voor de overige gebieden vormen klimaatimpact als de cumulatieve energievraag ('cumulative energy demand' CED) de maat voor de milieubelasting.

Transformation optics on a silicon platform

International Nuclear Information System (INIS)

Gabrielli, Lucas H; Lipson, Michal

2011-01-01

Transformation optics allows the creation of innovative devices; however, its implementation in the optical domain remains challenging. We describe here our process to design and fabricate such devices using silicon as a platform for broad band operation in the optical domain. We discuss the approximations and methods employed to overcome the challenges of using dielectric materials as a platform for transformation optics, such as the anisotropy and gradient refractive index implementation. These encompass conformal and quasi-conformal mappings, and a dithering process to discretize and quantize the continuously inhomogeneous index function. We show examples of devices that we fabricated and tested, including the carpet invisibility cloak, a broad bandwidth light concentrator, and a perfect imaging device, known as Maxwell's fish eye lens. Finally, we touch on future directions under investigation to further develop transformation optics based on dielectric materials

RAPID MONITORING BY QUANTITATIVE POLYMERASE CHAIN REACTION FOR PATHOGENIC ASPERGILLUS DURING CARPET REMOVAL FROM A HOSPITAL

Science.gov (United States)

Monitoring for pathogenic Aspergillus species using a rapid, highly sensitive, quantitative polumerase chain reaction technique during carpet removal in a burn unit provided data which allowed the patients to be safely returned to the re-floored area sooner than if only conventio...

77 FR 48505 - Submission for OMB Review; Comment Request-Flammability Standards for Carpets and Rugs

Science.gov (United States)

2012-08-14

... passing test results, then only one test per year is required. For purposes of estimating burden, we have... mail/hand delivery/courier (for paper, disk, or CD-ROM submissions), preferably in five copies, to... to perform each year varies, depending upon the number of carpet styles and the annual volume of...

Graphene based metamaterials for terahertz cloaking and subwavelength imaging

Science.gov (United States)

Forouzmand, Seyedali

Graphene is a two-dimensional carbon crystal that became one of the most controversial topics of research in the last few years. The intense interest in graphene stems from recent demonstrations of their potentially revolutionary electromagnetic applications -- including negative refraction, subdiffraction imaging, and even invisibility -- which have suggested a wide range of new devices for communications, sensing, and biomedicine. In addition, it has been shown that graphene is amenable to unique patterning schemes such as cutting, bending, folding, and fusion that are predicted to lead to interesting properties. A recent proposed application of graphene is in engineering the scattering properties of objects, which may be leveraged in applications such as radar-cross-section management and stealth, where it may be required to make one object look like another object or render an object completely invisible. We present the analytical formulation for the analysis of electromagnetic interaction with a finite conducting wedge covered with a cylindrically shaped nanostructured graphene metasurface, resulting in the scattering cancellation of the dominant scattering mode for all the incident and all the observation angles. Following this idea, the cylindrical graphene metasurface is utilized for cloaking of several concentric finite conducting wedges. In addition, a wedge shaped metasurface is proposed as an alternative approach for cloaking of finite wedges. The resolution of the conventional imaging lenses is restricted by the natural diffraction limit. Artificially engineered metamaterials now offer the possibility of creating a superlens that overcomes this restriction. We demonstrate that a wire medium (WM) slab loaded with graphene sheets enables the enhancement of the near field for subwavelength imaging at terahertz (THz) frequencies. The analysis is based on the nonlocal homogenization model for WM with the additional boundary condition in the connection of

Far-field high resolution effects and manipulating of electromagnetic waves based on transformation optics

Science.gov (United States)

Ji, XueBin; Zang, XiaoFei; Li, Zhou; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing

2015-05-01

Based on the transformation optics (TO) and the effective medium theory (EMT), a new illusion media with homogeneous and isotropic materials is proposed to realize the far-field high resolution effects. When two point sources with the separation distance of λ0 / 4 are covered with the illusion media (λ0 is the free-space wavelength), the corresponding far-field pattern is equivalent to the case of two point sources with the separation distance larger than λ0 / 2 in free space, leading to the far-field high resolution effects (in free space, the separation distance of λ0 / 4 is less than half-wavelength, and thus the two point sources cannot be distinguished from each other). Furthermore, such illusion media can be applied to design tunable high-directivity antenna and an angle-dependent floating carpet cloak. Full wave simulations are carried out to verify the performance of our device.

Partial elastodynamic cloaking by means of fiber-reinforced composites

International Nuclear Information System (INIS)

Olsson, P; Wall, David J N

2011-01-01

In this paper, we show that if inextensible fibers are embedded in an elastic material (or the material is by some other means made considerably stiffer in a particular but possibly variable direction), one may obtain equations of motion which are form invariant under certain diffeomorphism, allowing for partial cloaking (or 'illusion optics') schemes in both 2D and 3D. The schemes are valid at all frequencies without requiring any active material properties, and will thus work in the time domain without requiring active materials. While being mathematically exact at all frequencies, the applicability is of course limited to where the continuum approximation holds. Additional limits, set by idealization in the modeling of fibers and core material, are also present. However, contrary to some other approaches, the solution does not require metamaterials with non-scalar mass densities, nor does it require the breaking of the supersymmetry of the elasticity tensor

Partial elastodynamic cloaking by means of fiber-reinforced composites

Science.gov (United States)

Olsson, P.; Wall, David J. N.

2011-04-01

In this paper, we show that if inextensible fibers are embedded in an elastic material (or the material is by some other means made considerably stiffer in a particular but possibly variable direction), one may obtain equations of motion which are form invariant under certain diffeomorphism, allowing for partial cloaking (or 'illusion optics') schemes in both 2D and 3D. The schemes are valid at all frequencies without requiring any active material properties, and will thus work in the time domain without requiring active materials. While being mathematically exact at all frequencies, the applicability is of course limited to where the continuum approximation holds. Additional limits, set by idealization in the modeling of fibers and core material, are also present. However, contrary to some other approaches, the solution does not require metamaterials with non-scalar mass densities, nor does it require the breaking of the supersymmetry of the elasticity tensor.

Design of LTCC Based Fractal Antenna

KAUST Repository

AdbulGhaffar, Farhan

2010-01-01

The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array

Optical invisibility through metasurfaces made of plasmonic nanoparticles

Science.gov (United States)

Monti, A.; Alù, A.; Toscano, A.; Bilotti, F.

2015-03-01

In this paper, we investigate the application of the mantle cloaking technique to near-infrared and visible frequencies, analyzing and designing thin covers consisting of 2D arrays of plasmonic nanoparticles. First, we validate and generalize an analytical model recently appeared in the literature to describe a 2D array of plasmonic nanoparticles as a metasurface characterized by its homogenized surface reactance. We prove that the proposed model allows to efficiently design 2D mantle cloaks with an assigned surface reactance, enabling, thus, the extension of the mantle cloaking technique to optical frequencies. Then, we design realistic optical mantle cloaks made of 2D arrays of spheroidal plasmonic nanoparticles with a high eccentricity. We show that the proposed cloaks allow significant, moderately broadband cloaking effects at visible frequencies. In our designs, we consider realistic losses and non-critical nanoparticle dimensions to envision a practical realization of the proposed cloaks.

Prediction of short-term and long-term VOC emissions from SBR bitumen-backed carpet under different temperatures

NARCIS (Netherlands)

Yang, X.; Chen, Q.; Bluyssen, P.M.

1998-01-01

This paper presents two models for volatile organic compound (VOC) emissions from carpet. One is a numerical model using the computational fluid dynamics (CFD) tech-nique for short-term predictions, the other an analytical model for long-term predictions. The numerical model can (1) deal with

Electrostatic cloaking of surface structure for dynamic wetting

Science.gov (United States)

Shiomi, Junichiro; Nita, Satoshi; Do-Quang, Minh; Wang, Jiayu; Chen, Yu-Chung; Suzuki, Yuji; Amberg, Gustav

2017-11-01

Dynamic wetting problems are fundamental to the understanding of the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, as surfaces may often be naturally charged, or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena. Here we investigate the interplay between electric forces and surface structures in dynamic wetting. While surface microstructures can significantly hinder the spreading, we find that the electrostatics can ``cloak'' the microstructures, i.e. deactivate the hindering. We identify the physics in terms of reduction in contact-line friction, which makes the dynamic wetting inertial force dominant and insensitive to the substrate properties. This work was financially supported in part by, the Japan Society for the Promotion of Science, Swedish Governmental Agency for Innovation Systems, and the Japan Science and Technology Agency.

Extinction cross-section suppression and active acoustic invisibility cloaking

Science.gov (United States)

Mitri, F. G.

2017-10-01

Invisibility in its canonical form requires rendering a zero extinction cross-section (or energy efficiency) from an active or a passive object. This work demonstrates the successful theoretical realization of this physical effect for an active cylindrically radiating acoustic body, undergoing periodic axisymmetric harmonic vibrations near a flat rigid boundary. Radiating, amplification and extinction cross-sections of the active source are defined. Assuming monopole and dipole modal oscillations of the circular source, conditions are found where the extinction energy efficiency factor of the active source vanishes, achieving total invisibility with minimal influence of the source size. It also takes positive or negative values, depending on its size and distance from the boundary. Moreover, the amplification energy efficiency factor is negative for the acoustically-active source. These effects also occur for higher-order modal oscillations of the active source. The results find potential applications in the development of acoustic cloaking devices and invisibility.

Extinction cross-section suppression and active acoustic invisibility cloaking

International Nuclear Information System (INIS)

Mitri, F G

2017-01-01

Invisibility in its canonical form requires rendering a zero extinction cross-section (or energy efficiency) from an active or a passive object. This work demonstrates the successful theoretical realization of this physical effect for an active cylindrically radiating acoustic body, undergoing periodic axisymmetric harmonic vibrations near a flat rigid boundary. Radiating, amplification and extinction cross-sections of the active source are defined. Assuming monopole and dipole modal oscillations of the circular source, conditions are found where the extinction energy efficiency factor of the active source vanishes, achieving total invisibility with minimal influence of the source size. It also takes positive or negative values, depending on its size and distance from the boundary. Moreover, the amplification energy efficiency factor is negative for the acoustically-active source. These effects also occur for higher-order modal oscillations of the active source. The results find potential applications in the development of acoustic cloaking devices and invisibility. (letter)

The influence of temperature on the emission of volatile organic compounds from PVC flooring, carpet, and paint

NARCIS (Netherlands)

Wal, J.F. van der; Hoogeveen, A.W.; Wouda, P.

1997-01-01

The influence of temperature on the emission rate of volatile organic compounds (VOC) from four indoor materials was investigated in a small dynamic test chamber. The materials investigated were two carpets, a PVC flooring and a paint; the temperature range investigated was 23-50°C. The general

An Inquiry-Oriented Approach to Span and Linear Independence: The Case of the Magic Carpet Ride Sequence

Science.gov (United States)

Wawro, Megan; Rasmussen, Chris; Zandieh, Michelle; Sweeney, George Franklin; Larson, Christine

2012-01-01

In this paper we present an innovative instructional sequence for an introductory linear algebra course that supports students' reinvention of the concepts of span, linear dependence, and linear independence. Referred to as the Magic Carpet Ride sequence, the problems begin with an imaginary scenario that allows students to build rich imagery and…

Evaluation of occupational exposure of carpet weavers in northern province of Madhya Pradesh (India) during different seasons.

Science.gov (United States)

Wani, Khursheed Ahmad; Khan, Rejvan; Mamta

2015-01-01

We investigated general working conditions in the carpet manufacturing industry and assessed the health risk factors of weavers working in this industry. Noise level, light intensity, temperature and humidity were measured with the help of sound level meter, lux meter and thermohygrometer, respectively at the workplace and the result were subjected to One Way Analysis of Variance. A pretested questionnaire was used to evaluate the health problems among different weavers working in the carpet industry. Results indicated that the weavers in these units were exposed to extreme environmental conditions. The majority of these weavers were suffering from eye irritation, back pain, allergies, general weakness, hearing loss, with most workers having three to five of these health problems. Our study reported higher incidence of musculoskeletal and respiratory diseases among weavers, during different season. A large variation during different seasons is an indication that environmental conditions play an important role in determining the health of weavers at the workplace. Results clearly demonstrate that working conditions were not suitable for the type of work carried out by the weavers.

The Carpets and Karma: The Resilient Story of the Tibetan Community in Two Settlements in India and Nepal

Directory of Open Access Journals (Sweden)

Venkat Rao Pulla

2014-02-01

Full Text Available This paper is about the Tibetan people in two settlements, mainly in Nepal and India. Tibetan ref- ugees started crossing the Himalayan range in April 1959, in the wake of the Dalai Lama’s flight into exile and landed mostly in Nepal and India. Tibetans around the world do not know their fu- ture nor do they appear unduly worried. Most of them appear resilient and hopeful to see a ‘free Tibet’ a dream closer to their hearts, someday in the future. In this paper, we delve at their deep association between their philosophy of life based on the principles of ‘karma’ and their everyday economic avocation of weaving ‘carpets’. We find that these people weave their lives around kar- ma and the carpets. Karma embodies their philosophical and spiritual outlook while carpets, mats and paintings symbolise their day-to-day struggles, enterprises to cope, survive, thrive and flour- ish. The ‘karma carpet’ symbolises their journey into the future. The Tibetans although a refugee group do not have the same rights and privileges comparable to other refugees living in the world decreed under the United Nations Conventions. In this paper, we present the socio-economic situ- ation of these refugees, their enterprise and their work ethic that makes them who they are in the Nepalese and in Indian societies. For this research, we have triangulated both desk studies and personal narratives from focus groups and interviews to present a discussion centred on the Ti- betan struggle for human rights and their entrepreneurship through the carpet industry mainly in Nepal and India.

Production of activated carbons from waste carpets and its application in methylene blue adsorption: Kinetic and thermodynamic studies

Czech Academy of Sciences Publication Activity Database

Hassan, A F.; Elhadidy, Hassan

2017-01-01

Roč. 5, č. 1 (2017), s. 955-963 ISSN 2213-3437 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Waste carpets * Activated carbons * Adsorption * Kinetic Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

Making the Best Decisions: Designing for Excellence!

Science.gov (United States)

Bullock, Ann Adams; Foster-Harrison, Elizabeth S.

1997-01-01

Argues classrooms must provide an appropriately stimulating environment that supports learning and provides teachers and students with a comfortable place to learn. Lists requisite factors of the school environment including furniture, aesthetics, color, carpet, building maintenance, decorating detail, comfort, space/design, lighting, classroom…

Infrared Cloaking, Stealth, and the Second Law of Thermodynamics

Directory of Open Access Journals (Sweden)

Daniel P. Sheehan

2012-10-01

Full Text Available Infrared signature management (IRSM has been a primary aeronautical concern for over 50 years. Most strategies and technologies are limited by the second law of thermodynamics. In this article, IRSM is considered in light of theoretical developments over the last 15 years that have put the absolute status of the second law into doubt and that might open the door to a new class of broadband IR stealth and cloaking techniques. Following a brief overview of IRSM and its current thermodynamic limitations, theoretical and experimental challenges to the second law are reviewed. One proposal is treated in detail: a high power density, solid-state power source to convert thermal energy into electrical or chemical energy. Next, second-law based infrared signature management (SL-IRSM strategies are considered for two representative military scenarios: an underground installation and a SL-based jet engine. It is found that SL-IRSM could be technologically disruptive across the full spectrum of IRSM modalities, including camouflage, surveillance, night vision, target acquisition, tracking, and homing.

Full-Carpet Design of a Low-Boom Demonstrator Concept

Science.gov (United States)

Ordaz, Irian; Wintzer, Mathias; Rallabhandi, Sriram K.

2015-01-01

The Cart3D adjoint-based design framework is used to mitigate the undesirable o -track sonic boom properties of a demonstrator concept designed for low-boom directly under the flight path. First, the requirements of a Cart3D design mesh are determined using a high-fidelity mesh adapted to minimize the discretization error of the CFD analysis. Low-boom equivalent area targets are then generated at the under-track and one off-track azimuthal position for the baseline configuration. The under-track target is generated using a trim- feasible low-boom target generation process, ensuring that the final design is not only low-boom, but also trimmed at the specified flight condition. The o -track equivalent area target is generated by minimizing the A-weighted loudness using an efficient adjoint-based approach. The configuration outer mold line is then parameterized and optimized to match the off-body pressure distributions prescribed by the low-boom targets. The numerical optimizer uses design gradients which are calculated using the Cart3D adjoint- based design capability. Optimization constraints are placed on the geometry to satisfy structural feasibility. The low-boom properties of the final design are verified using the adaptive meshing approach. This analysis quantifies the error associated with the CFD mesh that is used for design. Finally, an alternate mesh construction and target positioning approach offering greater computational efficiency is demonstrated and verified.

Magnetic light cloaking control in the marine planktonic copepod Sapphirina

Science.gov (United States)

Kashiwagi, H.; Mizukawa, Y.; Iwasaka, M.; Ohtsuka, S.

2017-05-01

We investigated the light cloaking behavior of the marine planktonic copepod Sapphirina under a magnetic field. Optical interferences in the multi-laminated guanine crystal layer beneath the dorsal body surface create a brilliant structural color, which can be almost entirely removed by changing the light reflection. In the investigation, we immersed segments of Sapphirina in seawater contained in an optical chamber. When the derived Sapphirina segments were attached to the container surface, they were inert to magnetic fields up to 300 mT. However, when the back plate segments were attached to the substrate at a point, with most of the plate floating in the seawater, the plate rotated oppositely to the applied magnetic field. In addition, the brilliant parts of the Sapphirina back plate rotated backward and forward by changing the magnetic field directions. Our experiment suggests a new model of an optical micro-electro-mechanical system that is controllable by magnetic fields.

AHP 45: REVIEW: EARLY CARPETS AND TAPESTRIES ON THE EASTERN SILK ROAD

Directory of Open Access Journals (Sweden)

Juha Komppa

2017-03-01

Full Text Available Gloria Gonick’s book is the result of a series of detailed studies of some of the surviving Chinese Manichaean textiles, both in Japan and China.1 It has an ambitious composition and offers much more than the title announces. Less glamorous and more tribal than the many more studied luxury textiles, a mysterious group of thirty-six early painted tapestries and twenty-one carpets - all woolen - forms the focus of this study. They have been kept in Kyoto since the fourteenth and fifteenth centuries, as part of the local Gion Festival floats' decorations and have until recently been understood as ink-painted tapestries from Korea and regional wool-pile carpets from western China. Indeed, the Japanese notion of the tapestries as Korean made perfect sense in so far as the Japanese having acquired them largely from Korea in centuries past.2 In this context, it is worthwhile to mention Thomas Cole, who argues for a change in focus on Tibetan rugs from the conventional references to both Chinese and Buddhist influence. Instead, he suggests that the Tibetan weaving tradition should be viewed in a Central Asian tribal context.1 Similarly, Gonick looks for the provenance beyond Korea and successfully traces all of these textiles back to Gansu in China. This new provenance is a significant contribution of her study. Another is contextualizing the textiles within the Manichaean religion and the material culture it gave rise to. It is these textiles, seen and understood at long last as Manichaean relics, and preserved in China and Japan, that are the subject of her book. ...

RESTRICTIVE CARDIOMYOPATHY AND SECONDARY CONGESTIVE HEART FAILURE IN A MCDOWELL'S CARPET PYTHON (MORELIA SPILOTA MCDOWELLI).

Science.gov (United States)

Schilliger, Lionel; Chetboul, Valérie; Damoiseaux, Cécile; Nicolier, Alexandra

2016-12-01

Echocardiography is an established and noninvasive diagnostic tool used in herpetologic cardiology. Various cardiac lesions have been previously described in reptiles with the exception of restrictive cardiomyopathy. In this case report, restrictive cardiomyopathy and congestive heart failure associated with left atrial and sinus venosus dilation were diagnosed in a 2-yr-old captive lethargic McDowell's carpet python ( Morelia spilota mcdowelli), based on echocardiographic, Doppler, and histopathologic examinations. This cardiomyopathy was also associated with thrombosis within the sinus venosus.

Follow-up study of workers in a nylon carpet yarn plant after remedial actions taken against a contaminated humidification system

NARCIS (Netherlands)

Pal, TM; Groothoff, JW; Post, D; de Monchy, JGR

Objective: To investigate the effectiveness of remedial actions taken against a contaminated humidification system, after an outbreak of humidifier disease in a nylon carpet yam plant. Methods: Two and 6 years after modification, a follow-up investigation of a strati tied (age, smoking habits)

PRODUCTION OF AN INSULATION MATERIAL FROM CARPET AND BORON WASTES

Directory of Open Access Journals (Sweden)

Yasin ERDOĞAN

2016-12-01

Full Text Available Buildings are large consumers of energy in all countries. In regions with harsh climatic conditions, a substantial share of energy goes to heat and cool buildings. This paper reports an investigation of the insulation materials made from mixing carpet wastes with a solution with added crude colemanite ore, one of boron minerals, and a solution with added colemanite wastes from a barrage. A new building insulation material was produced which is name, Halibor. Optimum mixing ratios were determined for mass production and the physical properties of the product were established. In addition, the material produced was compared with similar products used in buildings in terms of physical properties. As a result of the investigations, it was established that the product provides high heat and sound insulation and can be used easily in building and construction industry.

Rigorous spin-spin correlation function of Ising model on a special kind of Sierpinski Carpets

International Nuclear Information System (INIS)

Yang, Z.R.

1993-10-01

We have exactly calculated the rigorous spin-spin correlation function of Ising model on a special kind of Sierpinski Carpets (SC's) by means of graph expansion and a combinatorial approach and investigated the asymptotic behaviour in the limit of long distance. The result show there is no long range correlation between spins at any finite temperature which indicates no existence of phase transition and thus finally confirms the conclusion produced by the renormalization group method and other physical arguments. (author). 7 refs, 6 figs

Task-Management Method Using R-Tree Spatial Cloaking for Large-Scale Crowdsourcing

Directory of Open Access Journals (Sweden)

Yan Li

2017-12-01

Full Text Available With the development of sensor technology and the popularization of the data-driven service paradigm, spatial crowdsourcing systems have become an important way of collecting map-based location data. However, large-scale task management and location privacy are important factors for participants in spatial crowdsourcing. In this paper, we propose the use of an R-tree spatial cloaking-based task-assignment method for large-scale spatial crowdsourcing. We use an estimated R-tree based on the requested crowdsourcing tasks to reduce the crowdsourcing server-side inserting cost and enable the scalability. By using Minimum Bounding Rectangle (MBR-based spatial anonymous data without exact position data, this method preserves the location privacy of participants in a simple way. In our experiment, we showed that our proposed method is faster than the current method, and is very efficient when the scale is increased.

Transformation optics with artificial Riemann sheets

Science.gov (United States)

Xu, Lin; Chen, Huanyang

2013-11-01

The two original versions of ‘invisibility’ cloaks (Leonhardt 2006 Science 312 1777-80 and Pendry et al 2006 Science 312 1780-2) show perfect cloaking but require unphysical singularities in material properties. A non-Euclidean version of cloaking (Leonhardt 2009 Science 323 110-12) was later presented to address these problems, using a very complicated non-Euclidean geometry. In this work, we combine the two original approaches to transformation optics into a more general concept: transformation optics with artificial Riemann sheets. Our method is straightforward and can be utilized to design new kinds of cloaks that can work not only in the realm of geometric optics but also using wave optics. The physics behind this design is similar to that of the conformal cloak for waves. The resonances in the interior region make the phase delay disappear and induce the cloaking effect. Numerical simulations confirm our theoretical results.

Effectiveness of house dust mite acaricide tri-n-butyl tin maleate on carpets, fabrics and mattress foam: a standardization of methodology Eficácia do acaricida maleato de estanho tri-n-butílico contra ácaros de poeira em carpetes, tecidos e espuma de colchão: padronização de metodologia

Directory of Open Access Journals (Sweden)

Satiko Uehara

2006-06-01

Full Text Available The aim of this study was to determine the effectiveness of the acaricide tri-n-butyl tin maleate, industrially applied to samples of carpets, mattress foam, and fabrics used for furniture upholstery, soft toys and shoe uppers. Approximately 100 adult house dust mites of the species Dermatophagoides pteronyssinus were inoculated into a Petri dish containing the sample (a piece of carpet, mattress foam, or fabric, treated with the acaricide, randomly collected. Mite-maintenance culture medium was added on top of each sample. After one, two, three, seven and 30 days of incubation at 25 ºC and 75% relative humidity, each dish was examined using a 40X stereoscopic microscope (40X. One hundred percent acaricide effectiveness was obtained in treated materials by the end of the 30th-day postinoculation period, under optimal conditions for mite maintenance.O objetivo do presente estudo foi verificar a eficácia do acaricida maleato de estanho tri-n-butílico, aplicado industrialmente em amostras de carpetes, tecidos de revestimentos de móveis e de calçados, assim como de espumas de colchão. Aproximadamente 100 ácaros adultos da espécie Dermatophagoides pteronyssinus foram inoculados em placa de Petri contendo a amostra (pedaço de colchão, tecido ou carpete, tratada com o produto acaricida, coletados aleatoriamente. Foi acrescentado sobre a amostra, meio de cultivo para a manutenção dos ácaros. Cada placa foi examinada após 1, 2, 3, 7 e 30 dias de incubação a 25 ºC e 75% de U.R.A. (umidade relativa do ar, sob microscópio estereoscópico com 40X de aumento. O acaricida maleato de estanho tri-n-butílico apresentou 100% de eficácia acaricida após 30 dias da aplicação, em condições ótimas para a manutenção dos ácaros.

Designing Industrial Networks Using Ecological Food Web Metrics.

Science.gov (United States)

Layton, Astrid; Bras, Bert; Weissburg, Marc

2016-10-18

Biologically Inspired Design (biomimicry) and Industrial Ecology both look to natural systems to enhance the sustainability and performance of engineered products, systems and industries. Bioinspired design (BID) traditionally has focused on a unit operation and single product level. In contrast, this paper describes how principles of network organization derived from analysis of ecosystem properties can be applied to industrial system networks. Specifically, this paper examines the applicability of particular food web matrix properties as design rules for economically and biologically sustainable industrial networks, using an optimization model developed for a carpet recycling network. Carpet recycling network designs based on traditional cost and emissions based optimization are compared to designs obtained using optimizations based solely on ecological food web metrics. The analysis suggests that networks optimized using food web metrics also were superior from a traditional cost and emissions perspective; correlations between optimization using ecological metrics and traditional optimization ranged generally from 0.70 to 0.96, with flow-based metrics being superior to structural parameters. Four structural food parameters provided correlations nearly the same as that obtained using all structural parameters, but individual structural parameters provided much less satisfactory correlations. The analysis indicates that bioinspired design principles from ecosystems can lead to both environmentally and economically sustainable industrial resource networks, and represent guidelines for designing sustainable industry networks.

Pushing, pulling and electromagnetic radiation force cloaking by a pair of conducting cylindrical particles

Science.gov (United States)

Mitri, F. G.

2018-02-01

The present analysis shows that two conducting cylindrical particles illuminated by an axially-polarized electric field of plane progressive waves at arbitrary incidence will attract, repel or become totally cloaked (i.e., invisible to the transfer of linear momentum carried by the incident waves), depending on their sizes, the interparticle distance as well as the angle of incidence of the incident field. Based on the rigorous multipole expansion method and the translational addition theorem of cylindrical wave functions, the electromagnetic (EM) radiation forces arising from multiple scattering effects between a pair of perfectly conducting cylindrical particles of circular cross-sections are derived and computed. An effective incident field on a particular particle is determined first, and used subsequently with its corresponding scattered field to derive the closed-form analytical expressions for the radiation force vector components. The mathematical expressions for the EM radiation force components (i.e. longitudinal and transverse) are exact, and have been formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the interparticle distance and the expansion coefficients. Numerical examples illustrate the analysis for two perfectly conducting circular cylinders in a homogeneous nonmagnetic medium of wave propagation. The computations for the dimensionless radiation force functions are performed with particular emphasis on varying the angle of incidence, the interparticle distance, and the sizes of the particles. Depending on the interparticle distance and angle of incidence, the cylinders yield total neutrality (or invisibility); they experience no force and become unresponsive to the transfer of the EM linear momentum due to multiple scattering cancellation effects. Moreover, pushing or pulling EM forces between the two cylinders arise depending on the interparticle distance, the angle of incidence and their

Transformation optics with artificial Riemann sheets

International Nuclear Information System (INIS)

Xu, Lin; Chen, Huanyang

2013-01-01

The two original versions of ‘invisibility’ cloaks (Leonhardt 2006 Science 312 1777–80 and Pendry et al 2006 Science 312 1780–2) show perfect cloaking but require unphysical singularities in material properties. A non-Euclidean version of cloaking (Leonhardt 2009 Science 323 110–12) was later presented to address these problems, using a very complicated non-Euclidean geometry. In this work, we combine the two original approaches to transformation optics into a more general concept: transformation optics with artificial Riemann sheets. Our method is straightforward and can be utilized to design new kinds of cloaks that can work not only in the realm of geometric optics but also using wave optics. The physics behind this design is similar to that of the conformal cloak for waves. The resonances in the interior region make the phase delay disappear and induce the cloaking effect. Numerical simulations confirm our theoretical results. (paper)

Innovative Basis of Research of Technologic Features of Some Craftsmanship Traditions of Ganja (On the Sample of Carpets of XIX Century)

Science.gov (United States)

Hasanov, Elnur L.

2016-01-01

The carpet production in Ganja took one of the leading handicraft activities since ancient times and still impresses with its high skill and the variety of colors, but there have been no widely studied the question of the creation technology of such representatives of cultural heritage. Scientific paper deals with the research of the basic…

The “Carpet-3” air shower array to search for diffuse gamma rays with energy Eγ>100TeV

Science.gov (United States)

Dzhappuev, D. D.; I, V. B. Petkov V.; Kudzhaev, A. U.; Lidvansky, A. S.; Volchenko, V. I.; Volchenko, G. V.; Gorbacheva, E. A.; Dzaparova, I. M.; Klimenko, N. F.; Kurenya, A. N.; Mikhilova, O. I.; Khadzhiev, M. M.; Yanin, A. F.

2017-12-01

At present an experiment for measuring the flux of cosmic diffuse gamma rays with energy higher than 100 TeV (experiment “Carpet-3”) is being prepared at the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences. The preparation of the experiment implies considerable enlargement of the area of both muon detector and surface part of the shower array. At the moment the plastic scintillation counters with a total continuous area of 410 m2 are installed in the muon detector (MD) underground tunnels, and they are totally equipped with electronics. Adjusting of the counters and their electronic circuits is in progress. Six modules of shower detectors (out of twenty planned to be installed) have already been placed on the surface of the MD absorber. A new liquid scintillation detector is developed for modules of the ground -surface part of the array, whose characteristics are presented. It is shown that the “Carpet-3” air shower array will have the best sensitivity to the flux of primary gamma rays with energies in the range 100TeV - 1PeV, being quite competitive in gamma-ray astronomy at such energies.

Presidential Green Chemistry Challenge: 2003 Designing Greener Chemicals Award

Science.gov (United States)

Presidential Green Chemistry Challenge 2003 award winner, Shaw Industries, developed EcoWorx carpet tiles with a backing that uses less toxic materials. The carpet tile fiber and backing are readily separated for recycling.

µ-XRF Studies on the Colour Brilliance in Ancient Wool Carpets

Directory of Open Access Journals (Sweden)

Markus Meyer

2017-01-01

Full Text Available Many handmade ancient and recent oriental wool carpets show outstanding brilliance and persistence of colour that is not achieved by common industrial dyeing procedures. Anthropologists have suggested the influence of wool fermentation prior to dyeing as key technique to achieve the high dyeing quality. By means of μ-XRF elemental mapping of mordant metals we corroborate this view and show a deep and homogenous penetration of colourants into fermented wool fibres. Furthermore we are able to apply this technique and prove that the fermentation process for ancient specimens cannot be investigated by standard methods due to the lack of intact cuticle layers. This finding suggests a broad range of further investigations that will contribute to a deeper understanding of the development of traditional dyeing techniques. Spectroscopic studies add information on the oxidation states of the metal ions within the respective mordant-dye-complexes and suggest a partial charge transfer as basis for a significant colour change when Fe mordants are used.

Preliminary study on the gamma radiation on the furniture carpet beetle Anthrenus flavipes LeConte (Coleoptera : Dermestidae)

International Nuclear Information System (INIS)

Hamad, B.Sh.; Khalaf, M.Z.; Jumaa, H.M.; Yasseen, N.H.; Al-Taweel, A.A.

2006-01-01

Preliminary study on the possibility of using gamma radiation to induce sexual sterility in males of the furniture carpet beetle A. Flavipes was carried out as a part of programme aiming to use SIT in controlling this pest. Results indicated that the induction of complete sterility in males was occurred by irradiated them as adults (24 hours old) by 100, 130 and 150 Gy. Furthermore, Results also showed that there was reducing in average number eggs laid by female that mated with irradiated male in comparison with females that matted with normal males

Spray-coated carbon nanotube carpets for creeping reduction of conducting polymer based artificial muscles

Science.gov (United States)

Simaite, Aiva; Delagarde, Aude; Tondu, Bertrand; Souères, Philippe; Flahaut, Emmanuel; Bergaud, Christian

2017-01-01

During cyclic actuation, conducting polymer based artificial muscles are often creeping from the initial movement range. One of the likely reasons of such behaviour is unbalanced charging during conducting polymer oxidation and reduction. To improve the actuation reversibility and subsequently the long time performance of ionic actuators, we suggest using spray-coated carbon nanotube (CNT) carpets on the surface of the conducting polymer electrodes. We show that carbon nanotubes facilitate a conducting polymer redox reaction and improve its reversibility. Consequently, in the long term, charge accumulation in the polymer film is avoided leading to a significantly improved lifetime performance during cycling actuation. To our knowledge, it is the first time a simple solution to an actuator creeping problem has been suggested.

Magnetic Carpet Probe for Large Area Instant Crack/Corrosion Detection and Health Monitoring

International Nuclear Information System (INIS)

Sun Yushi; Ouyang Tianhe; Yang Xinle; Zhu Haiou

2007-01-01

Recently a new NDE tool, Magnet Carpet Probe (MCP), has been developed by Innovative Materials Testing Technologies, Inc. supported by FAA to meet the demands of large area crack/corrosion detection and health monitoring. MCP is a two-dimensional coil array built on a piece of very thin flexible printed circuit board. A two-dimensional electromagnetic scan is going on within the MCP placed on top of a metallic surface under inspection. Therefore, one can finish the inspection, without moving anything, and see the crack/corrosion identification image on the instrument screen in a few second. Recent test results show that it can detect 0.030 x 0.016'' EDM notches on a Titanium standard; 0.024'' ∼ 0.036: real cracks on titanium standards, as well as penetrate through a 0.040'' aluminum layer for corrosion detection

Household vacuum cleaners vs. the high-volume surface sampler for collection of carpet dust samples in epidemiologic studies of children

Directory of Open Access Journals (Sweden)

Buffler Patricia A

2008-02-01

Full Text Available Abstract Background Levels of pesticides and other compounds in carpet dust can be useful indicators of exposure in epidemiologic studies, particularly for young children who are in frequent contact with carpets. The high-volume surface sampler (HVS3 is often used to collect dust samples in the room in which the child had spent the most time. This method can be expensive and cumbersome, and it has been suggested that an easier method would be to remove dust that had already been collected with the household vacuum cleaner. However, the household vacuum integrates exposures over multiple rooms, some of which are not relevant to the child's exposure, and differences in vacuuming equipment and practices could affect the chemical concentration data. Here, we compare levels of pesticides and other compounds in dust from household vacuums to that collected using the HVS3. Methods Both methods were used in 45 homes in California. HVS3 samples were collected in one room, while the household vacuum had typically been used throughout the home. The samples were analyzed for 64 organic compounds, including pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls (PCBs, using GC/MS in multiple ion monitoring mode; and for nine metals using conventional microwave-assisted acid digestion combined with ICP/MS. Results The methods agreed in detecting the presence of the compounds 77% to 100% of the time (median 95%. For compounds with less than 100% agreement, neither method was consistently more sensitive than the other. Median concentrations were similar for most analytes, and Spearman correlation coefficients were 0.60 or higher except for allethrin (0.15 and malathion (0.24, which were detected infrequently, and benzo(kfluoranthene (0.55, benzo(apyrene (0.55, PCB 105 (0.54, PCB 118 (0.54, and PCB 138 (0.58. Assuming that the HVS3 method is the "gold standard," the extent to which the household vacuum cleaner method yields relative risk

Wave Manipulation by Topology Optimization

DEFF Research Database (Denmark)

Andkjær, Jacob Anders

topology optimization can be used to design structures for manipulation of the electromagnetic and acoustic waves. The wave problems considered here fall within three classes. The first class concerns the design of cloaks, which when wrapped around an object will render the object undetectable...... for the cloak is to delay the waves in regions of higher permittivity than the background and subsequently phase match them to the waves outside. Directional acoustic cloaks can also be designed using the topology optimization method. Aluminum cylinders constitutes the design and their placement and size...... concerns the design of planar Fresnel zone plate lenses for focusing electromagnetic waves. The topology optimized zone plates improve the focusing performance compared to results known from the literature....

Three forms of omnidirectional acoustic invisibility engineered using fast elastodynamic transfer-matrix method

International Nuclear Information System (INIS)

Bowen, Patrick T; Urzhumov, Yaroslav A

2016-01-01

Acoustic metamaterial structures with discrete and continuous rotational symmetries attract interest of theorists and engineers due to the relative simplicity of their design and fabrication. They are also likely candidates for omnidirectional acoustic cloaking and other transformation-acoustical novelties. In this paper, we employ a stratified description of such structures, and develop the theory and an efficient symbolic/numerical algorithm for analyzing the scattering properties of such structures immersed in homogeneous fluid environments. The algorithm calculates the partial scattering amplitudes and the related scattering phases for an arbitrary layered distribution of acoustic material properties. The efficiency of the algorithm enables us to find approximate solutions to certain inverse scattering problems through quasi-global optimization. The scattering problems addressed here are the three forms of cloaking: (1) extinction cross-section suppression, the canonical form of cloaking, (2) monostatic sonar invisibility (backscattering suppression), and (3) acoustic force cloaking (transport cross-section suppression). We also address the efficiency-bandwidth tradeoff and design approximate cloaks with wider bandwidth using a new optimization formulation. (paper)

Three forms of omnidirectional acoustic invisibility engineered using fast elastodynamic transfer-matrix method

Science.gov (United States)

Bowen, Patrick T.; Urzhumov, Yaroslav A.

2016-04-01

Acoustic metamaterial structures with discrete and continuous rotational symmetries attract interest of theorists and engineers due to the relative simplicity of their design and fabrication. They are also likely candidates for omnidirectional acoustic cloaking and other transformation-acoustical novelties. In this paper, we employ a stratified description of such structures, and develop the theory and an efficient symbolic/numerical algorithm for analyzing the scattering properties of such structures immersed in homogeneous fluid environments. The algorithm calculates the partial scattering amplitudes and the related scattering phases for an arbitrary layered distribution of acoustic material properties. The efficiency of the algorithm enables us to find approximate solutions to certain inverse scattering problems through quasi-global optimization. The scattering problems addressed here are the three forms of cloaking: (1) extinction cross-section suppression, the canonical form of cloaking, (2) monostatic sonar invisibility (backscattering suppression), and (3) acoustic force cloaking (transport cross-section suppression). We also address the efficiency-bandwidth tradeoff and design approximate cloaks with wider bandwidth using a new optimization formulation.

Long-term and transient time variation of cosmic ray fluxes detected in Argentina by CARPET cosmic ray detector

Science.gov (United States)

De Mendonça, R. R. S.; Raulin, J.-P.; Bertoni, F. C. P.; Echer, E.; Makhmutov, V. S.; Fernandez, G.

2011-07-01

We present results obtained at El Leoncito (CASLEO, San Juan, Argentina) with the CARPET charged particles detector installed in April 2006. The observed modulation of the cosmic ray flux is discussed as a function of its time variability and it is related to longer solar activity variations and to shorter variations during solar and geomagnetic transient activity. Short period (few minutes, few hours) cosmic ray modulation events are observed during rain time (precipitation) and significant variations of the atmospheric electric field. Complementary observations of the atmospheric electric field indicate that its time variations play an important role in the detected cosmic ray event.

The RiSE climbing robot: body and leg design

Science.gov (United States)

Saunders, A.; Goldman, D. I.; Full, R. J.; Buehler, M.

2006-05-01

The RiSE robot is a biologically inspired, six legged climbing robot, designed for general mobility in scansorial (vertical walls, horizontal ledges, ground level) environments. It exhibits ground reaction forces that are similar to animal climbers and does not rely on suction, magnets or other surface-dependent specializations to achieve adhesion and shear force. We describe RiSE's body and leg design as well as its electromechanical, communications and computational infrastructure. We review design iterations that enable RiSE to climb 90° carpeted, cork covered and (a growing range of) stucco surfaces in the quasi-static regime.

Broadband omnidirectional invisibility for sound in three dimensions

OpenAIRE

Kan, Weiwei; Liang, Bin; Li, Ruiqi; Jiang, Xue; Zou, Xin-ye; Yin, Lei-lei; Cheng, Jianchun

2014-01-01

Acoustic cloaks that make object undetectable to sound waves have potential applications in a variety of scenarios and have received increasing interests recently. However, the experimental realization of a three-dimensional (3D) acoustic cloak that works within broad ranges of operating frequency and incident angle still remains a challenge despite the paramount importance for the practical application of cloaking devices. Here we report the design and experimental demonstration of the first...

Reshaping the perfect electrical conductor cylinder arbitrarily

International Nuclear Information System (INIS)

Chen Huanyang; Zhang Xiaohe; Luo Xudong; Ma Hongru; Chan Cheting

2008-01-01

A general method is proposed to design a cylindrical cloak, concentrator and superscatterer with an arbitrary cross section. The method is demonstrated by the design of a perfect electrical conductor (PEC) reshaper which is able to reshape a PEC cylinder arbitrarily by combining the concept of cloak, concentrator and superscatterer together. Numerical simulations are performed to demonstrate its properties.

Space-Filling Supercapacitor Carpets: Highly scalable fractal architecture for energy storage

Science.gov (United States)

Tiliakos, Athanasios; Trefilov, Alexandra M. I.; Tanasǎ, Eugenia; Balan, Adriana; Stamatin, Ioan

2018-04-01

Revamping ground-breaking ideas from fractal geometry, we propose an alternative micro-supercapacitor configuration realized by laser-induced graphene (LIG) foams produced via laser pyrolysis of inexpensive commercial polymers. The Space-Filling Supercapacitor Carpet (SFSC) architecture introduces the concept of nested electrodes based on the pre-fractal Peano space-filling curve, arranged in a symmetrical equilateral setup that incorporates multiple parallel capacitor cells sharing common electrodes for maximum efficiency and optimal length-to-area distribution. We elucidate on the theoretical foundations of the SFSC architecture, and we introduce innovations (high-resolution vector-mode printing) in the LIG method that allow for the realization of flexible and scalable devices based on low iterations of the Peano algorithm. SFSCs exhibit distributed capacitance properties, leading to capacitance, energy, and power ratings proportional to the number of nested electrodes (up to 4.3 mF, 0.4 μWh, and 0.2 mW for the largest tested model of low iteration using aqueous electrolytes), with competitively high energy and power densities. This can pave the road for full scalability in energy storage, reaching beyond the scale of micro-supercapacitors for incorporating into larger and more demanding applications.

Theory of transformation thermal convection for creeping flow in porous media: Cloaking, concentrating, and camouflage

Science.gov (United States)

Dai, Gaole; Shang, Jin; Huang, Jiping

2018-02-01

Heat can transfer via thermal conduction, thermal radiation, and thermal convection. All the existing theories of transformation thermotics and optics can treat thermal conduction and thermal radiation, respectively. Unfortunately, thermal convection has seldom been touched in transformation theories due to the lack of a suitable theory, thus limiting applications associated with heat transfer through fluids (liquid or gas). Here, we develop a theory of transformation thermal convection by considering the convection-diffusion equation, the equation of continuity, and the Darcy law. By introducing porous media, we get a set of equations keeping their forms under coordinate transformation. As model applications, the theory helps to show the effects of cloaking, concentrating, and camouflage. Our finite-element simulations confirm the theoretical findings. This work offers a transformation theory for thermal convection, thus revealing novel behaviors associated with potential applications; it not only provides different hints on how to control heat transfer by combining thermal conduction, thermal convection, and thermal radiation, but also benefits mass diffusion and other related fields that contain a set of equations and need to transform velocities at the same time.

Chromatographic and Spectroscopic Identification and Recognition of Natural Dyes, Uncommon Dyestuff Components, and Mordants: Case Study of a 16th Century Carpet with Chintamani Motifs

OpenAIRE

Olga Otłowska; Marek Ślebioda; Agata Kot-Wasik; Jakub Karczewski; Magdalena Śliwka-Kaszyńska

2018-01-01

A multi-tool analytical practice was used for the characterisation of a 16th century carpet manufactured in Cairo. A mild extraction method with hydrofluoric acid has been evaluated in order to isolate intact flavonoids and their glycosides, anthraquinones, tannins, and indigoids from fibre samples. High-performance liquid chromatography coupled to spectroscopic and mass spectrometric detectors was used for the identification of possible marker compounds with special attention paid to natural...

Topology optimization of nano-photonic systems

DEFF Research Database (Denmark)

Elesin, Yuriy; Wang, Fengwen; Andkjær, Jacob Anders

2012-01-01

We describe recent developments within nano-photonic systems design based on topology optimization. Applications include linear and non-linear optical waveguides, slow-light waveguides, as well as all-dielectric cloaks that minimize scattering or back-scattering from hard obstacles.......We describe recent developments within nano-photonic systems design based on topology optimization. Applications include linear and non-linear optical waveguides, slow-light waveguides, as well as all-dielectric cloaks that minimize scattering or back-scattering from hard obstacles....

A novel first aid stretcher for immobilization and transportation of spine injured patients.

Science.gov (United States)

Liu, Yan-Sheng; Feng, Ya-Ping; Xie, Jia-Xin; Luo, Zhuo-Jing; Shen, Cai-Hong; Niu, Fang; Zou, Jian; Tang, Shao-Feng; Hao, Jiang; Xu, Jia-Xiang; Xiao, Li-Ping; Xu, Xiao-Ming; Zhu, Hui

2012-01-01

Effective immobilization and transportation are vital to the life-saving acute medical care needed when treating critically injured people. However, the most common types of stretchers used today are wrought with problems that can lead to further medical complications, difficulty in employment and rescue, and ineffective transitions to hospital treatment. Here we report a novel first aid stretcher called the "emergency carpet", which solves these problems with a unique design for spine injured patients. Polyurethane composite material, obtained by a novel process of manually mixing isocyanate and additives, can be poured into a specially designed fabric bag and allowed to harden to form a rigid human-shaped stretcher. The effectiveness of the emergency carpet was examined in the pre-hospital management of victims with spinal fractures. Additionally, it was tested on flat ground and complex terrain as well as in the sea and air. We demonstrated that the emergency carpet can be assembled and solidified on the scene in 5 minutes, providing effective immobilization to the entire injured body. With the protection of the emergency carpet, none of the 20 patients, who were finally confirmed to have spinal column fracture or dislocation, had any neurological deterioration during transportation. Furthermore, the carpet can be handled and transported by multiple means under differing conditions, without compromising immobilization. Finally, the emergency carpet allows the critically injured patient to receive multiple examinations such as X-ray, CT, and MRI without being removed from the carpet. Our results demonstrate that the emergency carpet has ideal capabilities for immobilization, extrication, and transportation of the spine injured patients. Compared with other stretchers, it allows for better mobility, effective immobilization, remarkable conformity to the body, and various means for transportation. The emergency carpet is promising for its intrinsic advantages in

A novel first aid stretcher for immobilization and transportation of spine injured patients.

Directory of Open Access Journals (Sweden)

Yan-Sheng Liu

Full Text Available Effective immobilization and transportation are vital to the life-saving acute medical care needed when treating critically injured people. However, the most common types of stretchers used today are wrought with problems that can lead to further medical complications, difficulty in employment and rescue, and ineffective transitions to hospital treatment. Here we report a novel first aid stretcher called the "emergency carpet", which solves these problems with a unique design for spine injured patients. Polyurethane composite material, obtained by a novel process of manually mixing isocyanate and additives, can be poured into a specially designed fabric bag and allowed to harden to form a rigid human-shaped stretcher. The effectiveness of the emergency carpet was examined in the pre-hospital management of victims with spinal fractures. Additionally, it was tested on flat ground and complex terrain as well as in the sea and air. We demonstrated that the emergency carpet can be assembled and solidified on the scene in 5 minutes, providing effective immobilization to the entire injured body. With the protection of the emergency carpet, none of the 20 patients, who were finally confirmed to have spinal column fracture or dislocation, had any neurological deterioration during transportation. Furthermore, the carpet can be handled and transported by multiple means under differing conditions, without compromising immobilization. Finally, the emergency carpet allows the critically injured patient to receive multiple examinations such as X-ray, CT, and MRI without being removed from the carpet. Our results demonstrate that the emergency carpet has ideal capabilities for immobilization, extrication, and transportation of the spine injured patients. Compared with other stretchers, it allows for better mobility, effective immobilization, remarkable conformity to the body, and various means for transportation. The emergency carpet is promising for its

The Impact of Ergonomically Designed Workstations on Shoulder EMG Activity during Carpet Weaving

Directory of Open Access Journals (Sweden)

Majid Motamedzade

2014-12-01

Full Text Available Background: The present study aimed to evaluate the biomechanical exposure to the trapezius muscle activity in female weavers for a prolonged period in the workstation A (suggested by previous studies and workstation B (proposed by the present study. Methods: Electromyography data were collected from nine females during four hours for each ergonomically designed workstation at the Ergonomics Laboratory, Hamadan, Iran. The design criteria for ergonomically designed workstations were: 1 weaving height (20 and 3 cm above elbow height for workstations A and B, respectively, and 2 seat type (10° and 0° forwardsloping seat for workstations A and B, respectively. Results: The amplitude probability distribution function (APDF analysis showed that the left and right upper trapezius muscle activity was almost similar at each workstation. Trapezius muscle activity in the workstation A was significantly greater than workstations B (P<0.001. Conclusion: In general, use of workstation B leads to significantly reduced muscle activity levels in the upper trapezius as compared to workstation A in weavers. Despite the positive impact of workstation B in reducing trapezius muscle activity, it seems that constrained postures of the upper arm during weaving may be associated with musculoskeletal symptoms.

Method of moving frames to solve time-dependent Maxwell's equations on anisotropic curved surfaces: Applications to invisible cloak and ELF propagation

Science.gov (United States)

Chun, Sehun

2017-07-01

Applying the method of moving frames to Maxwell's equations yields two important advancements for scientific computing. The first is the use of upwind flux for anisotropic materials in Maxwell's equations, especially in the context of discontinuous Galerkin (DG) methods. Upwind flux has been available only to isotropic material, because of the difficulty of satisfying the Rankine-Hugoniot conditions in anisotropic media. The second is to solve numerically Maxwell's equations on curved surfaces without the metric tensor and composite meshes. For numerical validation, spectral convergences are displayed for both two-dimensional anisotropic media and isotropic spheres. In the first application, invisible two-dimensional metamaterial cloaks are simulated with a relatively coarse mesh by both the lossless Drude model and the piecewisely-parametered layered model. In the second application, extremely low frequency propagation on various surfaces such as spheres, irregular surfaces, and non-convex surfaces is demonstrated.

Decolorization of synthetic brilliant green carpet industry dye through fungal co-culture technology.

Science.gov (United States)

Kumari, Simpal; Naraian, Ram

2016-09-15

Aim of the present study was to evaluate the efficiency of fungal co-culture for the decolorization of synthetic brilliant green carpet industry dye. For this purpose two lignocellulolytic fungi Pleurotus florida (PF) and Rhizoctonia solani (RS) were employed. The study includes determination of enzyme profiles (laccase and peroxidase), dye decolorization efficiency of co-culture and crude enzyme extracts. Both fungi produced laccase and Mn peroxidase and successfully decolorized solutions of different concentrations (2.0, 4.0, 6.0, & 8.0(w/v) of dye. The co-culture resulted highest 98.54% dye decolorization at 2% (w/v) of dye as compared to monocultures (82.12% with PF and 68.89% with RS) during 12 days of submerged fermentation. The lower levels of dyes were rapidly decolorized, while higher levels in slow order as 87.67% decolorization of 8% dye. The promising achievement of the study was remarkable decolorizing efficiency of co-culture over monocultures. The direct treatment of the mono and co-culture enzyme extracts to dye also influenced remarkable. The highest enzymatic decolorization was through combined (PF and RS) extracts, while lesser by monoculture extracts. Based on the observations and potentiality of co-culture technology; further it can be exploited for the bioremediation of areas contaminated with hazardous environmental pollutants including textile and other industry effluents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integrated AHP and network DEA for assessing the efficiency of Iranian handmade carpet industry

Directory of Open Access Journals (Sweden)

Azadeh Omid

2015-09-01

Full Text Available Data envelopment analysis (DEA is a method for measuring the efficiency of peer decision making units (DMUs. Traditional DEA models deal with measurements of relative efficiency of DMUs regarding multiple-inputs vs. multiple-outputs. One of the drawbacks of these models is the neglect of intermediate products or linking activities. Recently, DEA has been extended to examine the efficiency of network structures, where there are lots of sub-processes that are linked with intermediate parameters. These intermediate parameters can be considered as the outputs of the first stage and simultaneously as the inputs for the second stage. In contrast to the traditional DEA analysis, network DEA analysis aims to measure different sub-processes’ efficiencies in addition to the total efficiency. Lots of network DEA technique has been used recently, but none of them uses Analytic Hierarchy Process (AHP in network DEA for assessing a network’s efficiency. In this paper, AHP methodology is used for considering the importance of each sub-process and network DEA is used for measuring total and partial efficiencies based on the importance of each department measured from AHP methodology. In this regard, the case of Iranian Handmade Carpet Industry (IHCI is used.

Interactive Universal Design Kiosks: Explanations About Social Inclusion Features in Architectural Design.

Science.gov (United States)

Guimarães, Marcelo Pinto; Picceli, Angélica Fátima Baldin; Sabino, Paulo Roberto

2016-01-01

This paper details a set of self-supporting and illuminated panels that work together but independently in order to emphasize the explanation of building features and activities that are based on Universal Design guidelines. The exhibition is based on two structures that are arranged in semi-circles (A and B). They are integrated to form a carpeted path where the visitor will be gradually exposed to the concepts related to the principles of Universal Design. Following the sequence of three-dimensional objects and swivelling box elements that support the tactile information on the subject, it is expected that visitors become familiar with each of the principles being demonstrated. Operated by a control system consisting of keys with colour signage, textures and high relief, the panel on the control table allows the user to choose information about paired relationships between some of seven principles contained in printed images about the architectural design on the set of panels. The effectiveness of the composition can be verified by the time people remain enough to hear, see and touch the kiosks for all the information, or by successive visits users make to the setting.

Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula.

Science.gov (United States)

Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A; Kriwet, Jürgen

2017-01-01

Seymour Island, Antarctic Peninsula, was once called the 'Rosetta Stone' of Southern Hemisphere palaeobiology, because this small island provides the most complete and richly fossiliferous Palaeogene sequence in Antarctica. Among fossil marine vertebrate remains, chondrichthyans seemingly were dominant elements in the Eocene Antarctic fish fauna. The fossiliferous sediments on Seymour Island are from the La Meseta Formation, which was originally divided into seven stratigraphical levels, TELMs 1-7 (acronym for Tertiary Eocene La Meseta) ranging from the upper Ypresian (early Eocene) to the late Priabonian (late Eocene). Bulk sampling of unconsolidated sediments from TELMs 5 and 6, which are Ypresian (early Eocene) and Lutetian (middle Eocene) in age, respectively, yielded very rich and diverse chondrichthyan assemblages including over 40 teeth of carpet sharks representing two new taxa, Notoramphoscyllium woodwardi gen. et sp. nov. and Ceolometlaouia pannucae gen. et sp. nov. Two additional teeth from TELM 5 represent two different taxa that cannot be assigned to any specific taxon and thus are left in open nomenclature. The new material not only increases the diversity of Eocene Antarctic selachian faunas but also allows two previous orectolobiform records to be re-evaluated. Accordingly, Stegostoma cf. faciatum is synonymized with Notoramphoscyllium woodwardi gen. et sp. nov., whereas Pseudoginglymostoma cf. brevicaudatum represents a nomen dubium . The two new taxa, and probably the additional two unidentified taxa, are interpreted as permanent residents, which most likely were endemic to Antarctic waters during the Eocene and adapted to shallow and estuarine environments.

Photonic Design: From Fundamental Solar Cell Physics to Computational Inverse Design

Science.gov (United States)

Miller, Owen Dennis

Photonic innovation is becoming ever more important in the modern world. Optical systems are dominating shorter and shorter communications distances, LED's are rapidly emerging for a variety of applications, and solar cells show potential to be a mainstream technology in the energy space. The need for novel, energy-efficient photonic and optoelectronic devices will only increase. This work unites fundamental physics and a novel computational inverse design approach towards such innovation. The first half of the dissertation is devoted to the physics of high-efficiency solar cells. As solar cells approach fundamental efficiency limits, their internal physics transforms. Photonic considerations, instead of electronic ones, are the key to reaching the highest voltages and efficiencies. Proper photon management led to Alta Device's recent dramatic increase of the solar cell efficiency record to 28.3%. Moreover, approaching the Shockley-Queisser limit for any solar cell technology will require light extraction to become a part of all future designs. The second half of the dissertation introduces inverse design as a new computational paradigm in photonics. An assortment of techniques (FDTD, FEM, etc.) have enabled quick and accurate simulation of the "forward problem" of finding fields for a given geometry. However, scientists and engineers are typically more interested in the inverse problem: for a desired functionality, what geometry is needed? Answering this question breaks from the emphasis on the forward problem and forges a new path in computational photonics. The framework of shape calculus enables one to quickly find superior, non-intuitive designs. Novel designs for optical cloaking and sub-wavelength solar cell applications are presented.

Metamaterial inspired electromagnetic applications role of intelligent systems

CERN Document Server

2017-01-01

This book focuses on the role of soft-computing-based electromagnetic computational engines in design and optimization of a wide range of electromagnetic applications. In addition to the theoretical background of metamaterials and soft-computing techniques, the book discusses novel electromagnetic applications such as tensor analysis for invisibility cloaking, metamaterial structures for cloaking applications, broadband radar absorbers, and antennas. The book will prove to be a valuable resource for academics and professionals, as well as military researchers working in the area of metamaterials.

Design of LTCC Based Fractal Antenna

KAUST Repository

AdbulGhaffar, Farhan

2010-09-01

The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array has been designed for the first time on Low Temperature Co-fired Ceramic (LTCC) based substrate. LTCC provides a suitable platform for the development of these antennas due to its properties of vertical stack up and embedded passives. The complete antenna concept involves integration of this fractal antenna array with a Fresnel lens antenna providing a total gain of 15dB which is appropriate for medium range radar applications. The thesis also presents a comparison between the designed fractal antenna and a conventional patch antenna outlining the advantages of fractal antenna over the later one. The fractal antenna has a bandwidth of 1.8 GHz which is 7.5% of the centre frequency (24GHz) as compared to 1.9% of the conventional patch antenna. Furthermore the fractal design exhibits a size reduction of 53% as compared to the patch antenna. In the end a sensitivity analysis is carried out for the fractal antenna design depicting the robustness of the proposed design against the typical LTCC fabrication tolerances.

Modular Flooring System

Science.gov (United States)

Thate, Robert

2012-01-01

The modular flooring system (MFS) was developed to provide a portable, modular, durable carpeting solution for NASA fs Robotics Alliance Project fs (RAP) outreach efforts. It was also designed to improve and replace a modular flooring system that was too heavy for safe use and transportation. The MFS was developed for use as the flooring for various robotics competitions that RAP utilizes to meet its mission goals. One of these competitions, the FIRST Robotics Competition (FRC), currently uses two massive rolls of broadloom carpet for the foundation of the arena in which the robots are contained during the competition. The area of the arena is approximately 30 by 72 ft (approximately 9 by 22 m). This carpet is very cumbersome and requires large-capacity vehicles, and handling equipment and personnel to transport and deploy. The broadloom carpet sustains severe abuse from the robots during a regular three-day competition, and as a result, the carpet is not used again for competition. Similarly, broadloom carpets used for trade shows at convention centers around the world are typically discarded after only one use. This innovation provides a green solution to this wasteful practice. Each of the flooring modules in the previous system weighed 44 lb (.20 kg). The improvements in the overall design of the system reduce the weight of each module by approximately 22 lb (.10 kg) (50 %), and utilize an improved "module-to-module" connection method that is superior to the previous system. The MFS comprises 4-by-4-ft (.1.2-by- 1.2-m) carpet module assemblies that utilize commercially available carpet tiles that are bonded to a lightweight substrate. The substrate surface opposite from the carpeted surface has a module-to-module connecting interface that allows for the modules to be connected, one to the other, as the modules are constructed. This connection is hidden underneath the modules, creating a smooth, co-planar flooring surface. The modules are stacked and strapped

Optimization of loss and gain multilayers for reducing the scattering of a perfect conducting cylinder

Science.gov (United States)

Zhen-Zhong, Yu; Guo-Shu, Zhao; Gang, Sun; Hai-Fei, Si; Zhong, Yang

2016-07-01

Reduction of electromagnetic scattering from a conducting cylinder could be achieved by covering it with optimized multilayers of normal dielectric and plasmonic material. The plasmonic material with intrinsic losses could degrade the cloaking effect. Using a genetic algorithm, we present the optimized design of loss and gain multilayers for reduction of the scattering from a perfect conducting cylinder. This multilayered structure is theoretically and numerically analyzed when the plasmonic material with low loss and high loss respectively is considered. We demonstrate by full-wave simulation that the optimized nonmagnetic gain-loss design can greatly compensate the decreased cloaking effect caused by loss material, which facilitates the realization of practical electromagnetic cloaking, especially in the optical range. Project supported by the Research Foundation of Jinling Institute of Technology, China (Grant No. JIT-B-201426), the Jiangsu Modern Education and Technology Key Project, China (Grant No. 2014-R-31984), the Jiangsu 333 Project Funded Research Project, China (Grant No. BRA2010004), and the University Science Research Project of Jiangsu Province, China (Grant No. 15KJB520010).

The Applicability of the Risk Analysis System in Tax Audit Effectiveness (A Sample Application on Gaziantep Carpet Sector

Directory of Open Access Journals (Sweden)

Atilla Ahmet UĞUR

2016-12-01

Full Text Available Tax audit which is an undeniable part of the correct collection of taxes covering a significant portion of public expenditure is increasingly important in our tax where the basis of the declaration is valid. The necessity of tax audit to be effective is accepted by everyone without a doubt, but the issue of efficiency in tax audit has always been a problem. The effectiveness of tax audit is increasingly important in terms of the fiscal policy of the country and therefore of general economic policy. Various options have been put forward on ways to improve the efficiency of tax audit. One of these options is the risk analysis method. Risk analysis is an activity in which taxpayer's activities are analyzed in terms of groups and sectors through the risk analysis system which is formed by collecting all kind of information data and statistics and it is the activity to identify risk areas in this way. In this sense this study addresses a sample application of the risk analysis system for the Gaziantep Carpet Sector.

Chromatographic and Spectroscopic Identification and Recognition of Natural Dyes, Uncommon Dyestuff Components, and Mordants: Case Study of a 16th Century Carpet with Chintamani Motifs.

Science.gov (United States)

Otłowska, Olga; Ślebioda, Marek; Kot-Wasik, Agata; Karczewski, Jakub; Śliwka-Kaszyńska, Magdalena

2018-02-06

A multi-tool analytical practice was used for the characterisation of a 16th century carpet manufactured in Cairo. A mild extraction method with hydrofluoric acid has been evaluated in order to isolate intact flavonoids and their glycosides, anthraquinones, tannins, and indigoids from fibre samples. High-performance liquid chromatography coupled to spectroscopic and mass spectrometric detectors was used for the identification of possible marker compounds with special attention paid to natural dyes present in the historical samples. Weld, young fustic, and soluble redwood dye were identified as the dye sources in yellow thread samples. Based on the developed method, it was possible to establish that red fibres were coloured with lac dye, whereas green fibre shades were obtained with indigo and weld. Tannin-containing plant material in combination with indigo and weld were used to obtain the brown hue of the thread. Hyphenation of high-performance liquid chromatography (HPLC) with quadrupole time-of-flight mass spectrometry (QTOF MS) and triple-quadrupole mass spectrometry (QqQ MS) enabled us to recognise four uncommon and thus-far unknown dye components that were also found in the historical samples. These compounds probably represent a unique fingerprint of dyed threads manufactured in a Turkish workshop. Scanning electron microscopy with energy-dispersive X-ray detector (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR) were used for the identification and characterisation of substrates and mordants present in the historical carpet. Carbon and oxygen were detected in large quantities as a part of the wool protein. The presence of aluminium, iron, and calcium indicated their usage as mordants. Trace amounts of copper, silica, and magnesium might originate from the contaminants. FT-IR analysis showed bands characteristic for woollen fibres and SEM micrographs defined the structure of the wool.

Chromatographic and Spectroscopic Identification and Recognition of Natural Dyes, Uncommon Dyestuff Components, and Mordants: Case Study of a 16th Century Carpet with Chintamani Motifs

Directory of Open Access Journals (Sweden)

Olga Otłowska

2018-02-01

Full Text Available A multi-tool analytical practice was used for the characterisation of a 16th century carpet manufactured in Cairo. A mild extraction method with hydrofluoric acid has been evaluated in order to isolate intact flavonoids and their glycosides, anthraquinones, tannins, and indigoids from fibre samples. High-performance liquid chromatography coupled to spectroscopic and mass spectrometric detectors was used for the identification of possible marker compounds with special attention paid to natural dyes present in the historical samples. Weld, young fustic, and soluble redwood dye were identified as the dye sources in yellow thread samples. Based on the developed method, it was possible to establish that red fibres were coloured with lac dye, whereas green fibre shades were obtained with indigo and weld. Tannin-containing plant material in combination with indigo and weld were used to obtain the brown hue of the thread. Hyphenation of high-performance liquid chromatography (HPLC with quadrupole time-of-flight mass spectrometry (QTOF MS and triple-quadrupole mass spectrometry (QqQ MS enabled us to recognise four uncommon and thus-far unknown dye components that were also found in the historical samples. These compounds probably represent a unique fingerprint of dyed threads manufactured in a Turkish workshop. Scanning electron microscopy with energy-dispersive X-ray detector (SEM-EDS and Fourier transform infrared spectroscopy (FT-IR were used for the identification and characterisation of substrates and mordants present in the historical carpet. Carbon and oxygen were detected in large quantities as a part of the wool protein. The presence of aluminium, iron, and calcium indicated their usage as mordants. Trace amounts of copper, silica, and magnesium might originate from the contaminants. FT-IR analysis showed bands characteristic for woollen fibres and SEM micrographs defined the structure of the wool.

Designing Phononic Crystals with Wide and Robust Band Gaps

Science.gov (United States)

Jia, Zian; Chen, Yanyu; Yang, Haoxiang; Wang, Lifeng

2018-04-01

Phononic crystals (PnCs) engineered to manipulate and control the propagation of mechanical waves have enabled the design of a range of novel devices, such as waveguides, frequency modulators, and acoustic cloaks, for which wide and robust phononic band gaps are highly preferable. While numerous PnCs have been designed in recent decades, to the best of our knowledge, PnCs that possess simultaneous wide and robust band gaps (to randomness and deformations) have not yet been reported. Here, we demonstrate that by combining the band-gap formation mechanisms of Bragg scattering and local resonances (the latter one is dominating), PnCs with wide and robust phononic band gaps can be established. The robustness of the phononic band gaps are then discussed from two aspects: robustness to geometric randomness (manufacture defects) and robustness to deformations (mechanical stimuli). Analytical formulations further predict the optimal design parameters, and an uncertainty analysis quantifies the randomness effect of each designing parameter. Moreover, we show that the deformation robustness originates from a local resonance-dominant mechanism together with the suppression of structural instability. Importantly, the proposed PnCs require only a small number of layers of elements (three unit cells) to obtain broad, robust, and strong attenuation bands, which offer great potential in designing flexible and deformable phononic devices.

Designing Phononic Crystals with Wide and Robust Band Gaps

Energy Technology Data Exchange (ETDEWEB)

Chen, Yanyu [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jia, Zian [State University of New York at Stony Brook; Yang, Haoxiang [State University of New York at Stony Brook; Wang, Lifeng [State University of New York at Stony Brook

2018-04-16

Phononic crystals (PnCs) engineered to manipulate and control the propagation of mechanical waves have enabled the design of a range of novel devices, such as waveguides, frequency modulators, and acoustic cloaks, for which wide and robust phononic band gaps are highly preferable. While numerous PnCs have been designed in recent decades, to the best of our knowledge, PnCs that possess simultaneous wide and robust band gaps (to randomness and deformations) have not yet been reported. Here, we demonstrate that by combining the band-gap formation mechanisms of Bragg scattering and local resonances (the latter one is dominating), PnCs with wide and robust phononic band gaps can be established. The robustness of the phononic band gaps are then discussed from two aspects: robustness to geometric randomness (manufacture defects) and robustness to deformations (mechanical stimuli). Analytical formulations further predict the optimal design parameters, and an uncertainty analysis quantifies the randomness effect of each designing parameter. Moreover, we show that the deformation robustness originates from a local resonance-dominant mechanism together with the suppression of structural instability. Importantly, the proposed PnCs require only a small number of layers of elements (three unit cells) to obtain broad, robust, and strong attenuation bands, which offer great potential in designing flexible and deformable phononic devices.

New Designs in the Museums

Directory of Open Access Journals (Sweden)

Nuri Özer Erbay

2016-07-01

Full Text Available Architectural structure of the museum shall be designed in an accessible way regarding safety. In these designs special needs of visitors shall be taken into consideration according to types thereof.  Architectural structure, topography and natural presence of the museum increase visitor accessibility.  Exhibition venue, showcases and platforms, staircases providing access to upstairs, stairs, slippery rugged surfaces and entrance and exit to the exhibition venue from the same door form inaccessible areas.   It mustn't be forgotten that special disabled visitors can create an unsafe environment for others. Existing designs in museums shall be redesigned to be made accessible by disabled persons.  Museum venues must be redesigned ad made accessible by disabled persons. All characteristics of visitors in museums should be taken into consideration and universal living spaces addressing integral attitude should be designed.  Museum environment designs with regard to visitor safety must be steady.  Ramps shouldn't be unnecessarily steep and slippery.  Floor tiles, carpets or other ground coatings must be attached each other in a safe way. Gaps in ground coating shouldn't exceed the radius of13 mm. Grounds with different colors should be used for highlighting the ground odds and drawing visitors' attention. A distinctive environment requirement should be provided for visitors especially who use walking sticks, crutches and wheelchairs and warning signs shouldn't be forgotten.

Platonic scattering cancellation for bending waves in a thin plate

KAUST Repository

Farhat, Mohamed

2014-04-10

We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry.

Platonic scattering cancellation for bending waves in a thin plate

KAUST Repository

Farhat, Mohamed; Chen, P.-Y.; Bagci, Hakan; Enoch, S.; Guenneau, S.; Alù , A.

2014-01-01

We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry.

Electromagnetic complementary media with arbitrary geometries and non-conformal boundaries

Science.gov (United States)

Liu, Guochang; Li, Chao; Chen, Chao; Fang, Guangyou

2014-06-01

A generalized folded transformation procedure is presented for the space with arbitrary shapes. General expressions for the constitute parameters of complementary media are deduced, which can be readily applied to design complementary media based transformation optics devices (CMTOD) with arbitrary shapes. It's no longer limited to the situation when the inner and outer boundaries of the CMTOD are conformal or similar shapes, and can be available for the non-conformal situations. Three kinds of CMTOD are designed and studied, which involves a super-lens, an external cloak that hides object outside the cloaking shell, and an illusion optics device that transforms one object to another. Full-wave simulations are carried out to validate the proposed approach. The generalization introduced here makes a step forward for the flexible design of CMTOD with arbitrary geometries.

Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

Energy Technology Data Exchange (ETDEWEB)

Morrison, Glenn Charles [Univ. of California, Berkeley, CA (United States)

1999-12-01

In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10

Metamaterial-enabled transformation optics

Science.gov (United States)

Landy, Nathan

Transformation Optics is a design methodology that uses the form invariance of Maxwell's equations to distort electromagnetic fields. This distortion is imposed on a region of space by mimicking a curvilinear coordinate system with prescribed magnetoelectric material parameters. By simply specifying the correct coordinate transformation, researchers have created such exotic devices as invisibility cloaks, ``perfect'' lenses, and illusion devices. Unfortunately, these devices typically require correspondingly exotic material parameters that do not occur in Nature. Researchers have therefore turned to complex artificial media known as metamaterials to approximate the desired responses. However, the metamaterial design process is complex, and there are limitations on the responses that they achieve. In this dissertation, we explore both the applicability and limitations of metamaterials in Transformation Optics design. We begin in Chapter 2 by investigating the freedoms available to use in the transformation optics design process itself. We show that quasi-conformal mappings may be used to alleviate some of the complexity of material design in both two- and three-dimensional design. We then go on in Chapter 3 to apply this method to the design of a transformation-optics modified optic. We show that even a highly-approximate implementation of such a lens would retain many of the key performance feautures that we would expect from a full material prescription. However, the approximations made in the design of our lens may not be valid in other areas of transformation optical design. For instance, the high-frequency approximations of our lens design ignore the effects of impedance mismatch, and the approximation is not valid when the material parameters vary on the order of a wavelength. Therefore, in Chapter 4 we use other freedoms available to us to design a full-parameter cloak of invisibility. By tailoring the electromagnetic environment of our cloak, we are able to

Broadband unidirectional invisibility for airborne sound

Science.gov (United States)

Kan, Weiwei; Guo, Mengping; Shen, Zhonghua

2018-05-01

We present a metafluid-based broadband cloak capable of guiding acoustic waves around obstacles along given directions while maintaining the wavefront undisturbed. The required parameter distribution of the proposed cloak is derived by coordinate transformation and practically implemented by employing the acoustic metafluid formed with periodically arranged slabs in acoustic chambers. The method for independently modulating the effective mass density and bulk modulus of the metafluid is developed by tuning the geometry parameters and the temperature of the acoustic chamber in a specific process. By virtue of this free-modulated method, the range of realizable effective parameters is substantially broadened, and the acoustic impedance of the anisotropic structures can be well matched to the background. The performance of the designed structure is quantitatively evaluated in the frequency range of 3-4 kHz by the averaged invisibility factor. The results show that the proposed cloak is effective in manipulating the acoustic field along the given direction and suppressing the wave scattering from the hidden object.

Roadmap on transformation optics

Science.gov (United States)

McCall, Martin; Pendry, John B.; Galdi, Vincenzo; Lai, Yun; Horsley, S. A. R.; Li, Jensen; Zhu, Jian; Mitchell-Thomas, Rhiannon C.; Quevedo-Teruel, Oscar; Tassin, Philippe; Ginis, Vincent; Martini, Enrica; Minatti, Gabriele; Maci, Stefano; Ebrahimpouri, Mahsa; Hao, Yang; Kinsler, Paul; Gratus, Jonathan; Lukens, Joseph M.; Weiner, Andrew M.; Leonhardt, Ulf; Smolyaninov, Igor I.; Smolyaninova, Vera N.; Thompson, Robert T.; Wegener, Martin; Kadic, Muamer; Cummer, Steven A.

2018-06-01

Transformation optics asks, using Maxwell’s equations, what kind of electromagnetic medium recreates some smooth deformation of space? The guiding principle is Einstein’s principle of covariance: that any physical theory must take the same form in any coordinate system. This requirement fixes very precisely the required electromagnetic medium. The impact of this insight cannot be overestimated. Many practitioners were used to thinking that only a few analytic solutions to Maxwell’s equations existed, such as the monochromatic plane wave in a homogeneous, isotropic medium. At a stroke, transformation optics increases that landscape from ‘few’ to ‘infinity’, and to each of the infinitude of analytic solutions dreamt up by the researcher, there corresponds an electromagnetic medium capable of reproducing that solution precisely. The most striking example is the electromagnetic cloak, thought to be an unreachable dream of science fiction writers, but realised in the laboratory a few months after the papers proposing the possibility were published. But the practical challenges are considerable, requiring meta-media that are at once electrically and magnetically inhomogeneous and anisotropic. How far have we come since the first demonstrations over a decade ago? And what does the future hold? If the wizardry of perfect macroscopic optical invisibility still eludes us in practice, then what compromises still enable us to create interesting, useful, devices? While three-dimensional (3D) cloaking remains a significant technical challenge, much progress has been made in two dimensions. Carpet cloaking, wherein an object is hidden under a surface that appears optically flat, relaxes the constraints of extreme electromagnetic parameters. Surface wave cloaking guides sub-wavelength surface waves, making uneven surfaces appear flat. Two dimensions is also the setting in which conformal and complex coordinate transformations are realisable, and the possibilities in

Assessment of vegetation establishment on tailings dam at an iron ore mining site of suburban Beijing, China, 7 years after reclamation with contrasting site treatment methods.

Science.gov (United States)

Yan, Demin; Zhao, Fangying; Sun, Osbert Jianxin

2013-09-01

Strip-mining operations greatly disturb soil, vegetation and landscape elements, causing many ecological and environmental problems. Establishment of vegetation is a critical step in achieving the goal of ecosystem restoration in mining areas. At the Shouyun Iron Ore Mine in suburban Beijing, China, we investigated selective vegetation and soil traits on a tailings dam 7 years after site treatments with three contrasting approaches: (1) soil covering (designated as SC), (2) application of a straw mat, known as "vegetation carpet", which contains prescribed plant seed mix and water retaining agent (designated as VC), on top of sand piles, and (3) combination of soil covering and application of vegetation carpet (designated as SC+VC). We found that after 7 years of reclamation, the SC+VC site had twice the number of plant species and greater biomass than the SC and VC sites, and that the VC site had a comparable plant abundance with the SC+VC site but much less biodiversity and plant coverage. The VC site did not differ with the SC site in the vegetation traits, albeit low soil fertility. It is suggested that application of vegetation carpet can be an alternative to introduction of topsoil for treatment of tailings dam with fine-structured substrate of ore sands. However, combination of topsoil treatment and application of vegetation carpet greatly increases vegetation coverage and plant biodiversity, and is therefore a much better approach for assisting vegetation establishment on the tailings dam of strip-mining operations. While application of vegetation carpet helps to stabilize the loose surface of fine-structured mine wastes and to introduce seed bank, introduction of fertile soil is necessary for supplying nutrients to plant growth in the efforts of ecosystem restoration of mining areas.

Controlling Thermal Conduction by Graded Materials

Science.gov (United States)

Ji, Qin; Huang, Ji-Ping

2018-04-01

Manipulating thermal conductivities are fundamentally important for controlling the conduction of heat at will. Thermal cloaks and concentrators, which have been extensively studied recently, are actually graded materials designed according to coordinate transformation approaches, and their effective thermal conductivity is equal to that of the host medium outside the cloak or concentrator. Here we attempt to investigate a more general problem: what is the effective thermal conductivity of graded materials? In particular, we perform a first-principles approach to the analytic exact results of effective thermal conductivities of materials possessing either power-law or linear gradation profiles. On the other hand, by solving Laplace’s equation, we derive a differential equation for calculating the effective thermal conductivity of a material whose thermal conductivity varies along the radius with arbitrary gradation profiles. The two methods agree with each other for both external and internal heat sources, as confirmed by simulation and experiment. This work provides different methods for designing new thermal metamaterials (including thermal cloaks and concentrators), in order to control or manipulate the transfer of heat. Support by the National Natural Science Foundation of China under Grant No. 11725521, by the Science and Technology Commission of Shanghai Municipality under Grant No. 16ZR1445100

Changing the scattering of sheltered targets

International Nuclear Information System (INIS)

Luo Yang; He Lianxing; Wang Yu; Chan, Helen L.W.; Zhu Shouzheng

2011-01-01

In this paper, we propose a kind of illusion cloak that does not provide invisibility but instead changes the scattering of a coated target to that of a totally different one. Different from other illusion cloaks such as those based on 'anti-object' or active sources, the proposed one is independent of the information of concealed targets or incident waves and can reshape the scattering of any targets. In addition, we also provide a general method to imitate arbitrary conductor line segments, as a special case of conductor reshaper. Electromagnetic (EM) simulations by a finite-element solver on detailed examples have been carried to validate the design.

Controlling lightwave in Riemann space by merging geometrical optics with transformation optics.

Science.gov (United States)

Liu, Yichao; Sun, Fei; He, Sailing

2018-01-11

In geometrical optical design, we only need to choose a suitable combination of lenses, prims, and mirrors to design an optical path. It is a simple and classic method for engineers. However, people cannot design fantastical optical devices such as invisibility cloaks, optical wormholes, etc. by geometrical optics. Transformation optics has paved the way for these complicated designs. However, controlling the propagation of light by transformation optics is not a direct design process like geometrical optics. In this study, a novel mixed method for optical design is proposed which has both the simplicity of classic geometrical optics and the flexibility of transformation optics. This mixed method overcomes the limitations of classic optical design; at the same time, it gives intuitive guidance for optical design by transformation optics. Three novel optical devices with fantastic functions have been designed using this mixed method, including asymmetrical transmissions, bidirectional focusing, and bidirectional cloaking. These optical devices cannot be implemented by classic optics alone and are also too complicated to be designed by pure transformation optics. Numerical simulations based on both the ray tracing method and full-wave simulation method are carried out to verify the performance of these three optical devices.

Hand forces exerted by long-term care staff when pushing wheelchairs on compliant and non-compliant flooring.

Science.gov (United States)

Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

2018-09-01

Purpose-designed compliant flooring and carpeting have been promoted as a means for reducing fall-related injuries in high-risk environments, such as long-term care. However, it is not known whether these surfaces influence the forces that long-term care staff exert when pushing residents in wheelchairs. We studied 14 direct-care staff who pushed a loaded wheelchair instrumented with a triaxial load cell to test the effects on hand force of flooring overlay (vinyl versus carpet) and flooring subfloor (concrete versus compliant rubber [brand: SmartCells]). During straight-line pushing, carpet overlay increased initial and sustained hand forces compared to vinyl overlay by 22-49% over a concrete subfloor and by 8-20% over a compliant subfloor. Compliant subflooring increased initial and sustained hand forces compared to concrete subflooring by 18-31% when under a vinyl overlay. In contrast, compliant flooring caused no change in initial or sustained hand forces compared to concrete subflooring when under a carpet overlay. Copyright © 2018 Elsevier Ltd. All rights reserved.

Detecting cryptic speciation in the widespread and morphologically conservative carpet chameleon (Furcifer lateralis) of Madagascar.

Science.gov (United States)

Florio, A M; Ingram, C M; Rakotondravony, H A; Louis, E E; Raxworthy, C J

2012-07-01

Species delimitation within recently evolved groups can be challenging because species may be difficult to distinguish morphologically. Following the General Lineage Concept, we apply a multiple evidence approach to assess species limits within the carpet chameleon Furcifer lateralis, which is endemic to Madagascar and exported in large numbers for the pet trade. Cryptic speciation within F. lateralis was considered likely because this species (1) has a vast distribution, (2) occupies exceptionally diverse habitats and (3) exhibits subtle regional differences in morphology. Phylogenetic trees reconstructed using nuclear and mitochondrial genes recovered three well-supported clades corresponding with geography. Morphological results based on canonical variates analysis show that these clades exhibit subtle differences in head casque morphology. Ecological niche modelling results found that these phylogenetic groups also occupy unique environmental space and exhibit patterns of regional endemism typical of other endemic reptiles. Combined, our findings provide diverse yet consistent evidence for the existence of three species. Consequently, we elevate the subspecies F. lateralis major to species rank and name a new species distributed in northern and western Madagascar. Initial ecological divergence, associated with speciation of F. lateralis in humid eastern habitat, fits the Ecographic Constraint model for species diversification in Madagascar. By contrast, the second speciation event provides some support for the Riverine Barrier model, with the Mangoky River possibly causing initial isolation between species. These findings thus support two contrasting models of speciation within closely related species and demonstrate the utility of applying a combined-evidence approach for detecting cryptic speciation. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Metamaterials

CERN Document Server

Cui, Tie Jun

2009-01-01

Includes an introduction to optical transformation theory, revealing invisible cloaks, EM concentrators, beam splitters, and new-type antennas. This title offers a presentation of general theory on artificial metamaterials composed of periodic structures, and coverage of a rapid design method for inhomogeneous metamaterials.

Illusion induced overlapped optics.

Science.gov (United States)

Zang, XiaoFei; Shi, Cheng; Li, Zhou; Chen, Lin; Cai, Bin; Zhu, YiMing; Zhu, HaiBin

2014-01-13

The traditional transformation-based cloak seems like it can only hide objects by bending the incident electromagnetic waves around the hidden region. In this paper, we prove that invisible cloaks can be applied to realize the overlapped optics. No matter how many in-phase point sources are located in the hidden region, all of them can overlap each other (this can be considered as illusion effect), leading to the perfect optical interference effect. In addition, a singular parameter-independent cloak is also designed to obtain quasi-overlapped optics. Even more amazing of overlapped optics is that if N identical separated in-phase point sources covered with the illusion media, the total power outside the transformation region is N2I0 (not NI0) (I0 is the power of just one point source, and N is the number point sources), which seems violating the law of conservation of energy. A theoretical model based on interference effect is proposed to interpret the total power of these two kinds of overlapped optics effects. Our investigation may have wide applications in high power coherent laser beams, and multiple laser diodes, and so on.

Effect of repeated mowing to reduce graminoid plant cover on the moss carpet at a Sphagnum farm in North America

Directory of Open Access Journals (Sweden)

M. Guêné-Nanchen

2017-09-01

Full Text Available Sphagnum farming is defined as the sustainable production of non-decomposed Sphagnum biomass on a cyclical and renewable basis. In this article, the influence and necessity of mowing graminoid plants to optimise Sphagnum growth in Sphagnum farming basins are examined. Repeated mowing was applied to reduce graminoid plant cover at two different stages of the production cycle (one-year-old and seven-year-old Sphagnum moss carpet at the beginning of the experiment at an experimental Sphagnum farm in eastern Canada. Sphagnum growth (cover, biomass, moss layer thickness was measured after three years of mowing. In addition, a greenhouse experiment was carried out to determine whether there is a threshold for graminoid plant cover beyond which mowing becomes necessary. Sphagnum cover and biomass were not affected by repeated mowing, even if mowing reduced the cover of graminoid plants. Thus, it appears that mowing is unnecessary if the dominant vascular species is a graminoid plant such as Eriophorum angustifolium, which accumulates minimal amounts of litter. Furthermore, high cover of Eriophorum angustifolium (up to 85 % did not affect Sphagnum cover in a density-controlled greenhouse experiment. When the specific goal is Sphagnum fibre production, decisions about control of graminoid plants should be made after considering the cover, life form and litter accumulation potentials of the dominant graminoid species involved.

Generative Audio Design: Emergent Sound Art for an Open World Interface

OpenAIRE

Nelson, Blair Robert

2012-01-01

Clink. Clank clink. Ink cling clong clang. Cank ling. Ang clang. Clink. Clink. Clink. Clink. Clock clink. Click. Click. Click click. Cling. Clink. Clink clock click. Clah cling clah clink. Clag king. Kink. Dink. Dank. Kank. Ka clang, clonk. Konp. Koh kah cloak clock klink donk. Dong kling. Pah. Klong. Kland. Dah koh. Onk. Donk. Dip. Ing dop. Dop drop drip. Drape kape. Drip. Drip. Drim dram. Dip kip. Rim ram. Hop. Hum. Dim. Kum. Dah dape. Dee. Drip. Drop. Krop din. Dink. Rang drahh. Rimmmm. Ra...

Navigation strategies as revealed by error patterns on the Magic Carpet test in children with cerebral palsy

Directory of Open Access Journals (Sweden)

Vittorio eBelmonti

2015-07-01

Full Text Available IntroductionShort-term memory develops differently in navigation vs. manual space. The Magic Carpet (MC is a novel navigation test derived from the Walking Corsi Test and the manual Corsi Block-tapping Task (CBT. The MC requires mental rotations and executive function. In Cerebral Palsy (CP, CBT and MC scores relate differently to clinical and lesional factors. Hypotheses of this study are: that frontal lesions specifically affect navigation in CP; that brain lesions affect MC cognitive strategies.Material and methodsTwenty-two children with spastic CP, aged 5 to 14 years, 14 with a unilateral and 8 with a bilateral form, underwent the CBT and the MC. Errors were classified into 7 patterns by a recently described algorithm. Brain lesions were quantified according to a novel semi-quantitative MRI scale. Control data were partially drawn from a previous study on 91 typically developing children.ResultsChildren with CP performed worse than controls on both tests. Right hemispheric impairment correlated with spatial memory. MC span was reduced less than CBT span and was more selectively related to right middle white-matter and frontal lesions. Error patterns were differently distributed in CP than in typical development and depended on right brain impairment: children with more extensive right lesions made more positional than sequential errors.DiscussionIn CP, navigation is affected only by extensive lesions involving the right frontal lobe. In addition, these are associated with abnormal cognitive strategies. Whereas in typical development positional errors, preserving serial order, increase with age and performance, in CP they are associated with poorer performance and more extensive right-brain lesions. The explanation may lie in lesion side: right brain is crucial for mental rotations, necessary for spatial updating. Left-lateralized spatial memory strategies, relying on serial order, are not efficient if not accompanied by right-brain spatial

Aligned Carbon Nanotube Arrays Bonded to Solid Graphite Substrates: Thermal Analysis for Future Device Cooling Applications

Directory of Open Access Journals (Sweden)

Betty T. Quinton

2018-05-01

Full Text Available Carbon nanotubes (CNTs are known for high thermal conductivity and have potential use as nano-radiators or heat exchangers. This paper focuses on the thermal performance of carpet-like arrays of vertically aligned CNTs on solid graphite substrates with the idea of investigating their behavior as a function of carpet dimensions and predicting their performance as thermal interface material (TIM for electronic device cooling. Vertically aligned CNTs were grown on highly oriented pyrolytic graphite (HOPG substrate, which creates a robust and durable all-carbon hierarchical structure. The multi-layer thermal analysis approach using Netzsch laser flash analysis system was used to evaluate their performance as a function of carpet height, from which their thermal properties can be determined. It was seen that the thermal resistance of the CNT array varies linearly with CNT carpet height, providing a unique way of decoupling the properties of the CNT carpet from its interface. This data was used to estimate the thermal conductivity of individual multi-walled nanotube strands in this carpet, which was about 35 W/m-K. The influence of CNT carpet parameters (aerial density, diameter, and length on thermal resistance of the CNT carpet and its potential advantages and limitations as an integrated TIM are discussed.

The role of the substrate surface morphology and water in growth of vertically aligned single-walled carbon nanotubes.

Science.gov (United States)

Pint, Cary; Pheasant, Sean; Nicholas, Nolan; Horton, Charles; Hauge, Robert

2008-11-01

Growth of high quality, vertically aligned single-walled carbon nanotubes (carpets) is achieved using a rapid insertion hot filament chemical vapor deposition (HF-CVD) technique. The effect of the substrate morphology on growth is explored by comparing carpets grown on epitaxially polished MgO substrates to those grown on "as-cut", macroscopically rough MgO substrates. Depending on the substrate morphology, we observe differences in both the overall carpet morphology as well as the diameter distribution of nanotubes grown in the carpet based on optical measurements. In addition, we explore the role of water in the growth of carpets on MgO and the conventional Al2O3 coated Si substrates. We find that the addition of a small amount of water is beneficial to the growth rates of the SWNT carpets, enhancing the growth rates by up to eight times.

Transformation electromagnetics and metamaterials fundamental principles and applications

CERN Document Server

Werner, Douglas H

2013-01-01

Transformation electromagnetics is a systematic design technique for optical and electromagnetic devices that enables novel wave-material interaction properties. The associated metamaterials technology for designing and realizing optical and electromagnetic devices can control the behavior of light and electromagnetic waves in ways that have not been conventionally possible. The technique is credited with numerous novel device designs, most notably the invisibility cloaks, perfect lenses and a host of other remarkable devices.Transformation Electromagnetics and Metamaterials: Fundamental Princ

External Hand Forces Exerted by Long-Term Care Staff to Push Floor-Based Lifts: Effects of Flooring System and Resident Weight.

Science.gov (United States)

Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

2016-09-01

The aim of this study was to investigate the effects of flooring type and resident weight on external hand forces required to push floor-based lifts in long-term care (LTC). Novel compliant flooring is designed to reduce fall-related injuries among LTC residents but may increase forces required for staff to perform pushing tasks. A motorized lift may offset the effect of flooring on push forces. Fourteen female LTC staff performed straight-line pushes with two floor-based lifts (conventional, motor driven) loaded with passengers of average and 90th-percentile resident weights over four flooring systems (concrete+vinyl, compliant+vinyl, concrete+carpet, compliant+carpet). Initial and sustained push forces were measured by a handlebar-mounted triaxial load cell and compared to participant-specific tolerance limits. Participants rated pushing difficulty. Novel compliant flooring increased initial and sustained push forces and subjective ratings compared to concrete flooring. Compared to the conventional lift, the motor-driven lift substantially reduced initial and sustained push forces and perceived difficulty of pushing for all four floors and both resident weights. Participants exerted forces above published tolerance limits only when using the conventional lift on the carpet conditions (concrete+carpet, compliant+carpet). With the motor-driven lift only, resident weight did not affect push forces. Novel compliant flooring increased linear push forces generated by LTC staff using floor-based lifts, but forces did not exceed tolerance limits when pushing over compliant+vinyl. The motor-driven lift substantially reduced push forces compared to the conventional lift. Results may help to address risk of work-related musculoskeletal injury, especially in locations with novel compliant flooring. © 2016, Human Factors and Ergonomics Society.

The Marginalization of Globally-Born Businesses:

DEFF Research Database (Denmark)

Rezaei, Shahamak

Persian carpets have long been a major commodity in the world market, controlled by the Tehran Carpet Bazaar and the Hamburg Free Harbour. Today about 200 private traders in the Hamburg Free Harbour area export their carpets to about 10,000 private carpet traders throughout the world , these being...... group of traders stick together in order to remain in control of this world-wide billion dollars trade while they, on the other hand, compete strongly amongst each other in their private businesses....

The Status of the ARGO Experiment at YBJ

Energy Technology Data Exchange (ETDEWEB)

Aielli, G. [Dipartimento di Fisica dell' Universita ' Tor Vergata' di Roma and INFN Sezione di Roma2 (Italy); Bacci, C. [Dipartimento di Fisica dell' Universita ' Roma Tre' di Roma and INFN Sezione di Roma3 (Italy); Bartoli, B. [Dipartimento di Fisica dell' Universita di Napoli and INFN Sezione di Napoli (Italy); Bernardini, P. [Dipartimento di Fisica dell' Universita di Lecce and INFN Sezione di Lecce (Italy); Bi, X.J. [Key Laboratory of Particle Astrophyics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Beijing (China); Bleve, C. [Dipartimento di Fisica dell' Universita di Lecce and INFN Sezione di Lecce (Italy); Bussino, S. [Dipartimento di Fisica dell' Universita ' Roma Tre' di Roma and INFN Sezione di Roma3 (Italy); Calabrese Melcarne, A.K. [Dipartimento di Fisica dell' Universita di Lecce and INFN Sezione di Lecce (Italy); Camarri, P. [Dipartimento di Fisica dell' Universita ' Tor Vergata' di Roma and INFN Sezione di Roma2 (Italy); Campana, D. [Dipartimento di Fisica dell' Universita di Napoli and INFN Sezione di Napoli (Italy); Cao, Z. [Key Laboratory of Particle Astrophyics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Beijing (China); Cardarelli, R. [Dipartimento di Fisica dell' Universita ' Tor Vergata' di Roma and INFN Sezione di Roma2 (Italy); Catalanotti, S.; Cavaliere, S. [Dipartimento di Fisica dell' Universita di Napoli and INFN Sezione di Napoli (Italy); Celio, P. [Dipartimento di Fisica dell' Universita ' Roma Tre' di Roma and INFN Sezione di Roma3 (Italy); Chen, S.Z.; Cheng, N. [Key Laboratory of Particle Astrophyics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, Beijing (China); Creti, P. [Dipartimento di Fisica dell' Universita di Lecce and INFN Sezione di Lecce(Italy); Cui, S.W. [Hebei Normal University, Shijiazhuang 050016, Hebei (China)] (and others)

2007-04-15

The ARGO-YBJ experiment, located at Yangbajing, Tibet, China, performed by a wide Sino-Italian collaboration, is designed to study cosmic rays, sub-TeV gamma ray sources and GeV Gamma Ray Burst (GRB) emission in the northern hemisphere, by means of detecting small size EAS (Extensive Air Shower) using a full coverage RPC (Resistive Plate Chamber) carpet. The central carpet of the detector is installed and put into operation to date, with 1900m{sup 2} of the carpet already operating since December 2004. With a trigger multiplicity of {>=}60 hits, corresponding to a primary mode energy of 2 TeV, the angular resolution of EAS measurements is < 1{sup o} for showers with more than 500 recorded hits. We report the preliminary results of data taking performed during 2005: the all-sky survey for gamma ray sources and the search for GRBs, as well as the cosmic ray spectrum up to about 100 TeV. The Forbush decrease of the cosmic ray flux during January, 2005 is observed using the ARGO data.

Carpet Aids Learning in High Performance Schools

Science.gov (United States)

Hurd, Frank

2009-01-01

The Healthy and High Performance Schools Act of 2002 has set specific federal guidelines for school design, and developed a federal/state partnership program to assist local districts in their school planning. According to the Collaborative for High Performance Schools (CHPS), high-performance schools are, among other things, healthy, comfortable,…

The Marginalization of Globally-Born Businesses: Ethnically Divided Trade in Hamburg and the World Economy

DEFF Research Database (Denmark)

Rezaei, Shahamak

2009-01-01

Problem statement: Persian carpets have long been a major commodity in the world. Persian carpets have long been a major commodity in the world market, controlled by the Tehran Carpet Bazaar and the Hamburg Free Harbor. Today about 200 private traders in the Hamburg Free Harbor area export...

Impact of Surface Type, Wheelchair Weight, and Axle Position on Wheelchair Propulsion by Novice Older Adults

Science.gov (United States)

Cowan, Rachel E.; Nash, Mark S.; Collinger, Jennifer L.; Koontz, Alicia M.; Boninger, Michael L.

2009-01-01

Objective To examine the impact of surface type, wheelchair weight, and rear axle position on older adult propulsion biomechanics. Design Crossover trial. Setting Biomechanics laboratory. Participants Convenience sample of 53 ambulatory older adults with minimal wheelchair experience (65−87y); men = 20, women = 33. Intervention Participants propelled 4 different wheelchair configurations over 4 surfaces; tile, low carpet, high carpet, and an 8% grade ramp (surface, chair order randomized). Chair configurations included: (1) unweighted chair with an anterior axle position, (2) 9.05kg weighted chair with an anterior axle position, (3) unweighted chair with a posterior axle position (Δ0.08m), and (4) 9.05kg weighted chair with a posterior axle position (Δ0.08m). Weight was added to a titanium folding chair, simulating the weight difference between very light and depot wheelchairs. Instrumented wheels measured propulsion kinetics. Main Outcome Measures Average self-selected velocity, push-frequency, stroke length, peak resultant and tangential force. Results Velocity decreased as surface rolling resistance or chair weight increased. Peak resultant and tangential forces increased as chair weight increased, surface resistance increased, and with a posterior axle position. The effect of a posterior axle position was greater on high carpet and the ramp. The effect of weight was constant, but more easily observed on high carpet and ramp. The effects of axle position and weight were independent of one another. Conclusion Increased surface resistance decreases self-selected velocity and increases peak forces. Increased weight decreases self-selected velocity and increases forces. Anterior axle positions decrease forces, more so on high carpet. Effects of weight and axle position are independent. Greatest reductions in peak forces occur in lighter chairs with anterior axle positions. PMID:19577019

Enhancing Transparency and Control When Drawing Data-Driven Inferences About Individuals.

Science.gov (United States)

Chen, Daizhuo; Fraiberger, Samuel P; Moakler, Robert; Provost, Foster

2017-09-01

Recent studies show the remarkable power of fine-grained information disclosed by users on social network sites to infer users' personal characteristics via predictive modeling. Similar fine-grained data are being used successfully in other commercial applications. In response, attention is turning increasingly to the transparency that organizations provide to users as to what inferences are drawn and why, as well as to what sort of control users can be given over inferences that are drawn about them. In this article, we focus on inferences about personal characteristics based on information disclosed by users' online actions. As a use case, we explore personal inferences that are made possible from "Likes" on Facebook. We first present a means for providing transparency into the information responsible for inferences drawn by data-driven models. We then introduce the "cloaking device"-a mechanism for users to inhibit the use of particular pieces of information in inference. Using these analytical tools we ask two main questions: (1) How much information must users cloak to significantly affect inferences about their personal traits? We find that usually users must cloak only a small portion of their actions to inhibit inference. We also find that, encouragingly, false-positive inferences are significantly easier to cloak than true-positive inferences. (2) Can firms change their modeling behavior to make cloaking more difficult? The answer is a definitive yes. We demonstrate a simple modeling change that requires users to cloak substantially more information to affect the inferences drawn. The upshot is that organizations can provide transparency and control even into complicated, predictive model-driven inferences, but they also can make control easier or harder for their users.

A Simple Survey Concerning the Approach of the Cleaning Companies to Mercury Spills

Directory of Open Access Journals (Sweden)

Derya Camur

2010-12-01

Full Text Available AIM: The aim of this study is to determine the knowledge of the cleaning companies in case of mercury spills at home. METHOD: Thirty-two cleaning companies were interviewed by a telephone survey. Two standard questions were asked to an authorized people of the company. “A manometer is broken on the carpet. The mercury in the manometer is all spilled on the wall to wall carpet in the living room. We want our carpet to be cleaned. Could you do it? How can be the carpet cleaned? Have you ever cleaned a carpet on which mercury was spilled?” It is stated that mercury spillage has happened just a very short time ago and nothing have been done after that. RESULTS: Fifty percent of the 32 companies work in Istanbul, 37.5% in Ankara and 22.5% in Izmir. Three companies from Ankara, five from Istanbul, one from Izmir stated that they have encountered with mercury spillage before. Three of the companies who have stated that the have not encountered with mercury spillage before, asked “What is mercury?” and one of them asked whether “Mercury is a communicable disease, isn’t it?”. Twenty-two of the interviewed cleaning companies stated that they could clean the carpet with stain remover and three of them offered vacuuming, one washing the carpet with carpet shampoo, one person cleaning the stain by wiping with alcohol/ethyl alcohol. Five of the companies stated that they could not clean the stain and one of them he has advised throwing the carpet away. CONCLUSION: In many developing countries there is no responsible association or institution for mercury spills. Such simple surveys may be very important in determining training and gaps concerning public health problems. [TAF Prev Med Bull 2010; 9(6.000: 557-562

Development of Plasmonically Cloaked Nanoparticles

International Nuclear Information System (INIS)

Burgett, Eric; Al-Sheikhly, Mohamad; Summers, Christopher

2015-01-01

An advanced in-pile multi-parameter reactor monitoring system is being proposed in this funding opportunity. The proposed effort brings cutting edge, high-fidelity optical measurement systems into the reactor environment in an unprecedented fashion, including in-core, in-cladding and in-fuel pellet itself. Unlike instrumented leads, the proposed system provides a unique solution to a multi-parameter monitoring need in core while being minimally intrusive in the reactor core. Detector designs proposed herein can monitor fuel compression and expansion in both the radial and axial dimensions as well as monitor linear power profiles and fission rates during the operation of the reactor. In addition to pressure, stress, strain, compression, neutron flux, neutron spectra, and temperature can be observed inside the fuel bundle and fuel rod using the proposed system. The proposed research aims at developing radiation-hard, harsh-environment multi-parameter systems for insertion into the reactor environment. The proposed research holds the potential to drastically increase the fidelity and precision of in-core instrumentation with little or no impact in the neutron economy in the reactor environment while providing a measurement system capable of operation for entire operating cycles. Significant work has been done over the last few years on the use of nanoparticle-based scintillators. Through the use of metamaterials, the PIs aim to develop planar neutron detectors and large-volume neutron detectors. These detectors will have high efficiencies for neutron detection and will have a high gamma discrimination capability.

Development of Plasmonically Cloaked Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Burgett, Eric [Idaho State Univ., Pocatello, ID (United States); Al-Sheikhly, Mohamad [Univ. of Maryland, College Park, MD (United States); Summers, Christopher [Georgia Inst. of Technology, Atlanta, GA (United States)

2015-05-18

An advanced in-pile multi-parameter reactor monitoring system is being proposed in this funding opportunity. The proposed effort brings cutting edge, high-fidelity optical measurement systems into the reactor environment in an unprecedented fashion, including in-core, in-cladding and in-fuel pellet itself. Unlike instrumented leads, the proposed system provides a unique solution to a multi-parameter monitoring need in core while being minimally intrusive in the reactor core. Detector designs proposed herein can monitor fuel compression and expansion in both the radial and axial dimensions as well as monitor linear power profiles and fission rates during the operation of the reactor. In addition to pressure, stress, strain, compression, neutron flux, neutron spectra, and temperature can be observed inside the fuel bundle and fuel rod using the proposed system. The proposed research aims at developing radiation-hard, harsh-environment multi-parameter systems for insertion into the reactor environment. The proposed research holds the potential to drastically increase the fidelity and precision of in-core instrumentation with little or no impact in the neutron economy in the reactor environment while providing a measurement system capable of operation for entire operating cycles. Significant work has been done over the last few years on the use of nanoparticle-based scintillators. Through the use of metamaterials, the PIs aim to develop planar neutron detectors and large-volume neutron detectors. These detectors will have high efficiencies for neutron detection and will have a high gamma discrimination capability.

Transf ormation thermotics and the manipulation of thermal energy

Institute of Scientific and Technical Information of China (English)

Xiangfan Xu; Baowen Li

2017-01-01

Thermal energy has been proposed to have ever greater potential for human beings if the heat carriers, pho-nons can be controlled in micron-scale as easy as its counterpart, electrons in solid. However, it is a challenge to control phonons due to its relatively short wavelength, which is in the order of a few nanometers to a few tens of nanometers. Alternatively, in macroscopical scale, functional thermal materials are used to control thermal energy. The transfor-mation of macroscopical thermal diffusion equation is proposed to obtain the asymmetrical thermal conductivity in real space. This new type of thermal functional materials helps to control heat flow and to realize thermal cloak and thermal camouflage. In this review, we summarize the recent advances in constructing thermal functional materials (also called thermal metamaterials). In SecⅠ, we discussed the history of functional materials and the principles of constructing thermal functional materials , special focus was given to the thermal cloak, followed by the realization of thermal cloak in SecⅡ.Thermal camouflage, based on the realization of thermal cloak, was discussed in SecⅢ, which is proposed to have great potentials in military usage. We stressed both the principle and practical based challenges in thermal cloak and thermal camouflage in SecⅣ, in which outlooks were also given. It is worth noting that thermal transports consist of thermal conduction, thermal convection and thermal radiation. Recent progresses on thermal functional materials are based on the transformation of thermotics, i.e. spacial distortion of thermal conducting path, leaving thermal convection and thermal radiation untouched. We hope, though this review paper, to encourage more researchers in China to engage in this field, and to accelerate the practical usage of thermal cloak and thermal camouflage.

From Nonradiating Sources to Directionally Invisible Objects

Science.gov (United States)

Hurwitz, Elisa

The goal of this dissertation is to extend the understanding of invisible objects, in particular nonradiating sources and directional nonscattering scatterers. First, variations of null-field nonradiating sources are derived from Maxwell's equations. Next, it is shown how to design a nonscattering scatterer by applying the boundary conditions for nonradiating sources to the scalar wave equation, referred to here as the "field cloak method". This technique is used to demonstrate directionally invisible scatterers for an incident field with one direction of incidence, and the influence of symmetry on the directionality is explored. This technique, when applied to the scalar wave equation, is extended to show that a directionally invisible object may be invisible for multiple directions of incidence simultaneously. This opens the door to the creation of optically switchable, directionally invisible objects which could be implemented in couplers and other novel optical devices. Next, a version of the "field cloak method" is extended to the Maxwell's electro-magnetic vector equations, allowing more flexibility in the variety of directionally invisible objects that can be designed. This thesis concludes with examples of such objects and future applications.

An Interior's Interior. The American Film Institute

Science.gov (United States)

Morton, David

1974-01-01

In the John F. Kennedy Center for the Performing Arts, architects have broken some old conventions and rules of good taste in designing offices and a film theater through intelligent use of space and tacky flowered carpeting, garish colors, and automobile hoods and fenders. (Author/MF)

Analysis in temporal regime of dispersive invisible structures designed from transformation optics

Science.gov (United States)

Gralak, B.; Arismendi, G.; Avril, B.; Diatta, A.; Guenneau, S.

2016-03-01

A simple invisible structure made of two anisotropic homogeneous layers is analyzed theoretically in temporal regime. The frequency dispersion is introduced and analytic expression of the transient part of the field is derived for large times when the structure is illuminated by a causal excitation. This expression shows that the limiting amplitude principle applies with transient fields decaying as the power -3 /4 of the time. The quality of the cloak is then reduced at short times and remains preserved at large times. The one-dimensional theoretical analysis is supplemented with full-wave numerical simulations in two-dimensional situations which confirm the effect of dispersion.

Design of silicon-based fractal antennas

KAUST Repository

Ghaffar, Farhan A.

2012-11-20

This article presents Sierpinski carpet fractal antennas implemented in conventional low resistivity (Ï =10 Ω cm) as well as high resistivity (Ï =1500 Ω cm) silicon mediums. The fractal antenna is 36% smaller as compared with a typical patch antenna at 24 GHz and provides 13% bandwidth on high resistivity silicon, suitable for high data rate applications. For the first time, an on-chip fractal antenna array is demonstrated in this work which provides double the gain of a single fractal element as well as enhanced bandwidth. A custom test fixture is utilized to measure the radiation pattern and gain of these probe-fed antennas. In addition to gain and impedance characterization, measurements have also been made to study intrachip communication through these antennas. The comparison between the low resistivity and high resistivity antennas indicate that the former is not a suitable medium for array implementation and is only suitable for short range communication whereas the latter is appropriate for short and medium range wireless communication. The design is well-suited for compact, high data rate System-on-Chip (SoC) applications as well as for intrachip communication such as wireless global clock distribution in synchronous systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:180-186, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27245 Copyright © 2012 Wiley Periodicals, Inc.

Design of silicon-based fractal antennas

KAUST Repository

Ghaffar, Farhan A.; Shamim, Atif

2012-01-01

This article presents Sierpinski carpet fractal antennas implemented in conventional low resistivity (Ï =10 Ω cm) as well as high resistivity (Ï =1500 Ω cm) silicon mediums. The fractal antenna is 36% smaller as compared with a typical patch antenna at 24 GHz and provides 13% bandwidth on high resistivity silicon, suitable for high data rate applications. For the first time, an on-chip fractal antenna array is demonstrated in this work which provides double the gain of a single fractal element as well as enhanced bandwidth. A custom test fixture is utilized to measure the radiation pattern and gain of these probe-fed antennas. In addition to gain and impedance characterization, measurements have also been made to study intrachip communication through these antennas. The comparison between the low resistivity and high resistivity antennas indicate that the former is not a suitable medium for array implementation and is only suitable for short range communication whereas the latter is appropriate for short and medium range wireless communication. The design is well-suited for compact, high data rate System-on-Chip (SoC) applications as well as for intrachip communication such as wireless global clock distribution in synchronous systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:180-186, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27245 Copyright © 2012 Wiley Periodicals, Inc.

Cardboard Houses with Wings: The Architecture of Alabama's Rural Studio

Science.gov (United States)

Botz-Bornstein, Thorsten

2010-01-01

The Rural Studio, an outreach program of Auburn University, designs innovative houses for poor people living in Alabama's Hale County by using "junk" such as car windshields, carpet tiles, baled cardboard, and old license plates. The article theorizes this particular architecture in terms of Critical Regionalism, developed by…

Multiple Learning Strategies Project. Building Maintenance & Engineering. Educable Mentally Impaired. [Vol. 2.

Science.gov (United States)

Constantini, Debra; And Others

This instructional package is one of three designed for educable mentally impaired students in the vocational area of building maintenance and engineering. The thirty-four learning modules are organized into six units: general maintenance tasks; restrooms; chalkboards; carpet care; office cleaning; and grounds. Each module includes these elements:…

Multiple Learning Strategies Project. Building Maintenance & Engineering. Visually Impaired.

Science.gov (United States)

Smith, Dwight; And Others

This instructional package is designed for visually impaired students in the vocational area of building maintenance and engineering. The twenty-eight learning modules are organized into six units: floor care, general maintenance tasks; restrooms; carpet care; power and hand tools; and cabinet construction. Each module, printed in large block…

Multiple Learning Strategies Project. Building Maintenance & Engineering. Low Reader. [Vol. 2.

Science.gov (United States)

Steinberg, A.; And Others

This instructional package is one of two designed for low reader students (those reading at grade level 3-6) in the vocational area of building maintenance and engineering. The forty-four learning modules are organized into eleven units: chalkboards; carpet care; office cleaning; grounds; sanitation; boiler maintenance and operation; power and…

Designing a social and assistive robot for seniors.

Science.gov (United States)

Eftring, H; Frennert, S

2016-06-01

The development of social assistive robots is an approach with the intention of preventing and detecting falls among seniors. There is a need for a relatively low-cost mobile robot with an arm and a gripper which is small enough to navigate through private homes. User requirements of a social assistive robot were collected using workshops, a questionnaire and interviews. Two prototype versions of a robot were designed, developed and tested by senior citizens (n = 49) in laboratory trials for 2 h each and in the private homes of elderly persons (n = 18) for 3 weeks each. The user requirement analysis resulted in a specification of tasks the robot should be able to do to prevent and detect falls. It was a challenge but possible to design and develop a robot where both the senior and the robot arm could reach the necessary interaction points of the robot. The seniors experienced the robot as happy and friendly. They wanted the robot to be narrower so it could pass through narrow passages in the home and they also wanted it to be able to pass over thresholds without using ramps and to drive over carpets. User trials in seniors' homes are very important to acquire relevant knowledge for developing robots that can handle real life situations in the domestic environment. Very high reliability of a robot is needed to get feedback about how seniors experience the overall behavior of the robot and to find out if the robot could reduce falls and improve the feeling of security for seniors living alone.

“ALGORITHMIC SUSTAINABLE DESIGN: THE FUTURE OF ARCHITECTURAL THEORY”, A SERIES OF 12 LECTURES BY NIKOS A. SALINGAROS.

Directory of Open Access Journals (Sweden)

Nicola Giacomo A.G. Linza IV

2008-07-01

Full Text Available Professor Nikos A. Salingaros, a practicing Urbanist and Architectural Theorist, presents a powerful series of compelling hour-long lectures that apply cutting-edge mathematical techniques to architectural design. This breakthrough lecture series seeks to explain the foundations of architectural form using scientific concepts from hierarchical scaling to memes. Dr. Salingaros has applied the most exciting scientific developments of the past decade, such as fractals, complexity theory, evolutionary biology, and artificial intelligence to produce a series of lectures explaining in great detail the mathematical and scientific basis behind structure, and how structures affect the way in which human beings interact with the built environment. The twelve lectures were integrated to relate topics such as algorithmic processes, cellular automata, Sierpinski carpets, harmony-seeking computations, generative codes, and New Urbanist codes. The lectures were transmitted live via streaming video to participating institutions throughout the world, and have now been made freely available.

Photonic metamaterials

International Nuclear Information System (INIS)

Litchinitser, N M; Shalaev, V M

2008-01-01

The invention of metamaterials prompts reconsideration of a number of fundamental physical phenomena and enables a variety of unique properties and functionalities. These include negative refractive index, magnetism at optical frequencies, sub-wavelength resolution, ''backward'' phase matching conditions for nonlinear optical processes, and even rendering objects invisible – cloaking. In this brief review, recent progress in basic theory, design, fabrication, characterization, and potential applications of optical metamaterials is discussed

Bryophytes as indicators of radiocesium deposition in northeastern Italy

International Nuclear Information System (INIS)

Giovani, C.; Nimis, P.L.; Bolognini, G.; Padovani, R.; Usco, A.

1994-01-01

Samples of moss carpets growing in forest vegetation have been used to map radioactive fallout in northeastern Italy. The main factors affecting data variability are the inclination of the carpets, water absorbing power, and their thickness. The best suited bioindicator proved to be Ctenidium molluscum. The results indicate that these carpets were able to intercept most of the radiocesium deposited after the Chernobyl accident, and that the removal half-time in the survey area is of circa 46 months

WebQuest on Conic Sections as a Learning Tool for Prospective Teachers

Science.gov (United States)

Kurtulus, Aytac; Ada, Tuba

2012-01-01

WebQuests incorporate technology with educational concepts through integrating online resources with student-centred and activity-based learning. In this study, we describe and evaluate a WebQuest based on conic sections, which we have used with a group of prospective mathematics teachers. The WebQuest entitled: "Creating a Carpet Design Using…

Conceptional design of a novel next-generation cryogenic stopping cell for the Low-Energy Branch of the Super-FRS

Energy Technology Data Exchange (ETDEWEB)

Dickel, T., E-mail: t.dickel@gsi.de [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Plaß, W.R.; Geissel, H. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Heiße, F. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden (Germany); Miskun, I. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); Purushothman, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Reiter, M.P.; Rink, A.-K. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); Scheidenberger, C. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany)

2016-06-01

The conceptual design of a next-generation cryogenic stopping cell (CSC) for the Low-Energy Branch (LEB) of the Super-FRS has been developed. It builds on advanced techniques implemented in the prototype version of the CSC, which has recently been commissioned as part of the FRS Ion Catcher with {sup 238}U projectile and fission fragments produced at 1000 MeV/u. These techniques include cryogenic operation to ensure a high purity of the stopping gas and high-density operation enabled using an RF carpet with a small electrode structure size. The next generation CSC implements several novel concepts (e.g. perpendicular extraction) which lead to enhanced performance compared to the prototype CSC: (i) extremely short extraction times, (ii) higher rate capability, (iii) increased areal density without deteriorating extraction times, efficiencies or rate capability, (iv) minimized RF power, (v) precise range measurement of the ions and (vii) improved cleanliness of the CSC.

Theoretical and Numerical Modeling of Acoustic Metamaterials for Aeroacoustic Applications

Directory of Open Access Journals (Sweden)

Umberto Iemma

2016-05-01

Full Text Available The advent, during the first decade of the 21st century, of the concept of acoustic metamaterial has disclosed an incredible potential of development for breakthrough technologies. Unfortunately, the extension of the same concepts to aeroacoustics has turned out to be not a trivial task, because of the different structure of the governing equations, characterized by the presence of the background aerodynamic convection. Some of the approaches recently introduced to circumvent the problem are biased by a fundamental assumption that makes the actual realization of devices extremely unlikely: the metamaterial should guarantee an adapted background aerodynamic convection in order to modify suitably the acoustic field and obtain the desired effect, thus implying the porosity of the cloaking device. In the present paper, we propose an interpretation of the metamaterial design that removes this unlikely assumption, focusing on the identification of an aerodynamically-impermeable metamaterial capable of reproducing the surface impedance profile required to achieve the desired scattering abatement. The attention is focused on a moving obstacle impinged by an acoustic perturbation induced by a co-moving source. The problem is written in a frame of reference rigidly connected to the moving object to couple the convective wave equation in the hosting medium with the inertially-anisotropic wave operator within the cloak. The problem is recast in an integral form and numerically solved through a boundary-field element method. The matching of the local wave vector is used to derive a convective design of the metamaterial applicable to the specific problem analyzed. Preliminary numerical results obtained under the simplifying assumption of a uniform aerodynamic flow reveal a considerable enhancement of the masking capability of the convected design. The numerical method developed shows a remarkable computational efficiency, completing a simulation of the entire

Morphing for faster computations in transformation optics.

Science.gov (United States)

Aznavourian, Ronald; Guenneau, Sébastien

2014-11-17

We propose to use morphing algorithms to deduce some approximate wave pictures of scattering by cylindrical invisibility cloaks of various shapes deduced from the exact computation (e.g. using a finite element method) of scattering by cloaks of two given shapes, say circular and elliptic ones, thereafter called the source and destination images. The error in L(2) norm between the exact and approximate solutions deduced via morphing from the source and destination images is typically less than 2 percent if control points are judiciously chosen. Our approach works equally well for rotators and concentrators, and also unveils some device which we call rotacon since it both rotates and concentrates electromagnetic fields. However, it breaks down for superscatterers (deduced from non-monotonic transforms): the error in L(2) norm is about 25 percent. We stress that our approach might greatly accelerate numerical studies of 2D and 3D cloaks.

Impact of Mass and Weight Distribution on Manual Wheelchair Propulsion Torque.

Science.gov (United States)

Sprigle, Stephen; Huang, Morris

2015-01-01

Propulsion effort of manual wheelchairs, a major determinant of user mobility, is a function of human biomechanics and mechanical design. Human studies that investigate both variables simultaneously have resulted in largely inconsistent outcomes, motivating the implementation of a robotic propulsion system that characterizes the inherent mechanical performance of wheelchairs. This study investigates the impacts of mass and mass distribution on manual wheelchair propulsion by configuring an ultra-lightweight chair to two weights (12-kg and 17.6-kg) and two load distributions (70% and 55% on drive wheels). The propulsion torques of these four configurations were measured for a straight maneuver and a fixed-wheel turn, on both tile and carpet. Results indicated that increasing mass to 17.6-kg had the largest effect on straight acceleration, requiring 7.4% and 5.8% more torque on tile and carpet, respectively. Reducing the drive wheel load to 55% had the largest effect on steady-state straight motion and on both turning acceleration and steady-state turning; for tile and carpet, propulsion torque increased by 13.5% and 11.8%, 16.5% and 4.1%, 73% and 5.1%, respectively. These results demonstrate the robot's high sensitivity, and support the clinical importance of evaluating effects of wheelchair mass and axle position on propulsion effort across maneuvers and surfaces.

Acoustically induced transparency using Fano resonant periodic arrays

KAUST Repository

El-Amin, Mohamed

2015-10-22

A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

Acoustically induced transparency using Fano resonant periodic arrays

KAUST Repository

El-Amin, Mohamed; Elayouch, A.; Farhat, Mohamed; Addouche, M.; Khelif, A.; Bagci, Hakan

2015-01-01

A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

House Dust Mite Prevalence in the House of Patients with Atopic Dermatitis in Mashhad, Iran

Directory of Open Access Journals (Sweden)

Toktam Ziyaei

2017-06-01

Full Text Available Background: Being exposed to house dust mites intensifies atopic dermatitis. This study has investigated the con­tamination rate with Dermatophagoides mites in patient's residential home with atopic dermatitis.Methods: In this cross-sectional study, 40 patients took part with atopic dermatitis (positive or negative for mites by prick Dermal Test. Samples were collected from 3 locations (living room, bedroom and bed by vacuum cleaner. Dust samples (transferred to freezer -20 ˚C were examined by direct method and flotation. The data were analyzed using statistical SPSS vr.20 software.Results: Twenty patients of positive prick test included 8 (40% male and 12 (60% female. The results of direct observation of mites: 7 cases (35% in bedding sheets, 6 cases (30% bedrooms' carpet, 3 cases (15% living room's carpet. Twenty patients of negative prick test included 8 (40% male and 12 (60% female. Only mites were found (5% in living room's carpets of negative prick test patients. Dermatophagoides pteronyssinus was more frequent than Dermatophagoides farinae. (98% vs 83%.Conclusion: Fifty-five percent of residential homes of prick test positive patients and only 5% of residential homes of prick test negative patients were positive for mite. Sunshine provided home had fewer mites than home where sunshine is not provided. Prick test positive patients used handmade carpets more than machine made ones. In posi­tive prick test patients, mites were found in bed sheet and bedroom’s carpet more than negative prick test patient's sheets and carpets.

Comparison between full- and small-scale sensory assessments of air quality

DEFF Research Database (Denmark)

Wargocki, Pawel; Sabikova, J.; Lagercrantz, Love Per

2002-01-01

Thirty-nine untrained subjects made small- and full-scale evaluations of the acceptability of the quality of air at 22 deg.C and 40% RH, polluted by either carpet, felt floor covering, painted gypsum board, linoleum or chipboard. Small-scale evaluations were made on the air extracted from 200-L......-scale sensory ratings of acceptability of air polluted by carpet and by linoleum were systematically better than small-scale assessments, but not for the other three materials. Calculated sensory emission rates from carpet and linoleum were significantly lower in full scale than in small scale. When modelling...

Fast Adaptive Thermal Camouflage Based on Flexible VO₂/Graphene/CNT Thin Films.

Science.gov (United States)

Xiao, Lin; Ma, He; Liu, Junku; Zhao, Wei; Jia, Yi; Zhao, Qiang; Liu, Kai; Wu, Yang; Wei, Yang; Fan, Shoushan; Jiang, Kaili

2015-12-09

Adaptive camouflage in thermal imaging, a form of cloaking technology capable of blending naturally into the surrounding environment, has been a great challenge in the past decades. Emissivity engineering for thermal camouflage is regarded as a more promising way compared to merely temperature controlling that has to dissipate a large amount of excessive heat. However, practical devices with an active modulation of emissivity have yet to be well explored. In this letter we demonstrate an active cloaking device capable of efficient thermal radiance control, which consists of a vanadium dioxide (VO2) layer, with a negative differential thermal emissivity, coated on a graphene/carbon nanotube (CNT) thin film. A slight joule heating drastically changes the emissivity of the device, achieving rapid switchable thermal camouflage with a low power consumption and excellent reliability. It is believed that this device will find wide applications not only in artificial systems for infrared camouflage or cloaking but also in energy-saving smart windows and thermo-optical modulators.

77 FR 34027 - Proposed Extension of Approval of Information Collection; Comment Request-Testing and...

Science.gov (United States)

2012-06-08

... Management and Budget (OMB), of information collection requirements for manufacturers and importers of... each year varies, depending upon the number of carpet styles and the annual volume of production. CPSC... one to 200, depending upon the number of carpet styles and the annual production volume. For example...

The Role of Interface on the Impact Characteristics and Cranial Fracture Patterns Using the Immature Porcine Head Model.

Science.gov (United States)

Deland, Trevor S; Niespodziewanski, Emily; Fenton, Todd W; Haut, Roger C

2016-01-01

The role of impact interface characteristics on the biomechanics and patterns of cranial fracture has not been investigated in detail, and especially for the pediatric head. In this study, infant porcine skulls aged 2-19 days were dropped with an energy to cause fracturing onto four surfaces varying in stiffness from a rigid plate to one covered with plush carpeting. Results showed that heads dropped onto the rigid surface produced more extensive cranial fracturing than onto carpeted surfaces. Contact forces generated at fracture initiation and the overall maximum contact forces were generally lower for the rigid than carpeted impacts. While the degree of cranial fracturing from impacts onto the heavy carpeted surface was comparable to that of lower-energy rigid surface impacts, there were fewer diastatic fractures. This suggests that characteristics of the cranial fracture patterns may be used to differentiate energy level from impact interface in pediatric forensic cases. © 2015 American Academy of Forensic Sciences.

24 CFR 200.945 - Supplementary specific requirements under the HUD building product standards and certification...

Science.gov (United States)

2010-04-01

... under the HUD building product standards and certification program for carpet. 200.945 Section 200.945... requirements under the HUD building product standards and certification program for carpet. (a) Applicable.... (b) Labeling. Under the procedures set forth in § 200.935(d)(6) concerning labeling of a product, the...

Digging up the Dirt.

Science.gov (United States)

Knuffman, Susan M.

1997-01-01

Explores ways of maintaining school floors and carpeting that ensure students and staff are comfortable, safe, and healthy. Carpet maintenance for high- to low-traffic areas and cleaning procedures are examined, as are ways maintenance staff can work together to help ensure a successful flooring-maintenance plan. (GR)

Electromagnetic Field Control and Optimization Using Metamaterials

Science.gov (United States)

2009-12-01

Popović, and K. Hingerl. “Imperfect cloak- ing devices based on metamaterials,” Acta Physica Polonica A , 112(5):1083– 1088, 2007. 148 44. Jiang, Wei X...f. Jcpq Date Accepted: ... M ( A T~ 󈧢 S’t’P 2 GCt:f M. U. Thomas Date Dean, Graduate School of Engineering and Management APIT/DEE/ENG/09-13...dictated by the theory are inhomogeneous, anisotropic, and, in some instances, singular at various locations. In order for a cloak to be practically

Indoor Fungal and Bacterial Contaminations on Household Environment in Riyadh, Saudi Arabia

International Nuclear Information System (INIS)

Alwakeel, Suaad S

2008-01-01

This study was conducted to determine the microbial and inhabitant of household environment in Riyadh, Saudi Arabia. Overall, a total of 180 samples were collected and analyzed for fungal growth, 160 house samples were obtained on BAP medium and PDA medium. The Eastern Riyadh region turned out with the highest fungal isolates with 15/61 (24.6%). Among the most common fungal isolates from bedroom carpets were Aspergillus niger (21.6%), Alternaria sp. (15.7%), Aspergillus flavus (15.7%) Candida sp. (11.8%), Cladosporium sp. (9.8%) and Rhizopus sp. (9.8%). Other fungal isolates from bedroom carpets included Penicillium sp (5.9%)., Cunninghamella sp.(3.9%), Rhodotorula sp.(3.9%) and Aspergillus terreus (1.9%) Overall relative densities from all specimens obtained from household carpets, bedroom walls and carpet stores showed Alternaria spp. as the most common fungal isolate (55.3%) followed by Aspergillus niger (29%), Aspergillus flavus (19.3%), Rhizopus spp. (9.7%) and Penicillium spp. (7.0%). Other fungal isolates such as Candida spp., Cladosporium spp., Cunninghamella spp., Rhodotorula spp. and Aspergillus terreus had less than 6% overall relative density. From 40 carpet specimens collected for microbial analysis, 20 (50%) showed bacterial growth. Bacillus spp. was the most common isolated organism (35%) followed by Staphylococcus epidermidis (10%), Epiococcus spp. (10%), Corynebacterium spp. (10%) and Bacillus polymyxa (10%). Other bacterial isolates included Bacillus subtilis, Pseudomonas aeruginosa, Bacteroides spp., Clostridium spp. and Staphylococcus aureus .The presence of these fungal and microbial pathogens poses risk for individuals. When possible, floor carpeting in homes should be minimized or avoided since this serves as habitats for opportunistic fungi and infectious agents that pose harm to one's health. (author)

Illusion thermodynamics: A camouflage technique changing an object into another one with arbitrary cross section

International Nuclear Information System (INIS)

He, Xiao; Wu, Linzhi

2014-01-01

The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreement with the analytical results of the thermal illusion device

Illusion thermodynamics: A camouflage technique changing an object into another one with arbitrary cross section

Energy Technology Data Exchange (ETDEWEB)

He, Xiao; Wu, Linzhi, E-mail: wlz@hit.edu.cn [Center for Composite Materials, Harbin Institute of Technology, Harbin 150001 (China)

2014-12-01

The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreement with the analytical results of the thermal illusion device.

Impacts of a clay plaster on indoor air quality assessed using chemical and sensory measurements

DEFF Research Database (Denmark)

Darling, Erin K.; Cros, Clement J.; Wargocki, Pawel

2012-01-01

plaster as a PRM for improving air quality by controlling ozone, perceived air quality (PAQ) was determined in the presence of eight combinations of an emitting and reactive pollutant source (new carpet), clay plaster applied to gypsum wallboard, and chamber air with and without ozone. A panel of 24 human....... Perceived air quality was most acceptable and concentrations of aldehydes were lowest when only clay plaster or both clay plaster and carpet were present in the chambers without ozone. The least acceptable PAQ and the highest concentrations of aldehydes were observed when carpet and ozone were present...... together; addition of clay plaster for this condition improved PAQ and considerably decreased aldehyde concentrations....

Randomised controlled double-blind non-inferiority trial of two antivenoms for saw-scaled or carpet viper (Echis ocellatus envenoming in Nigeria.

Directory of Open Access Journals (Sweden)

Isa S Abubakar

Full Text Available BACKGROUND: In West Africa, envenoming by saw-scaled or carpet vipers (Echis ocellatus causes great morbidity and mortality, but there is a crisis in supply of effective and affordable antivenom (ISRCTN01257358. METHODS: In a randomised, double-blind, controlled, non-inferiority trial, "EchiTAb Plus-ICP" (ET-Plus equine antivenom made by Instituto Clodomiro Picado was compared to "EchiTAb G" (ET-G ovine antivenom made by MicroPharm, which is the standard of care in Nigeria and was developed from the original EchiTAb-Fab introduced in 1998. Both are caprylic acid purified whole IgG antivenoms. ET-G is monospecific for Echis ocellatus antivenom (initial dose 1 vial and ET-Plus is polyspecific for E. ocellatus, Naja nigricollis and Bitis arietans (initial dose 3 vials. Both had been screened by pre-clinical and preliminary clinical dose-finding and safety studies. Patients who presented with incoagulable blood, indicative of systemic envenoming by E. ocellatus, were recruited in Kaltungo, north-eastern Nigeria. Those eligible and consenting were randomly allocated with equal probability to receive ET-Plus or ET-G. The primary outcome was permanent restoration of blood coagulability 6 hours after the start of treatment, assessed by a simple whole blood clotting test repeated 6, 12, 18, 24 and 48 hr after treatment. Secondary (safety outcomes were the incidences of anaphylactic, pyrogenic and late serum sickness-type antivenom reactions. FINDINGS: Initial doses permanently restored blood coagulability at 6 hours in 161/194 (83.0% of ET-Plus and 156/206 (75.7% of ET-G treated patients (Relative Risk [RR] 1.10 one-sided 95% CI lower limit 1.01; P = 0.05. ET-Plus caused early reactions on more occasions than did ET-G [50/194 (25.8% and 39/206 (18.9% respectively RR (1.36 one-sided 95% CI 1.86 upper limit; P = 0.06. These reactions were classified as severe in 21 (10.8% and 11 (5.3% of patients, respectively. CONCLUSION: At these doses, ET-Plus was

Technology in Use

Science.gov (United States)

Glazner, Steve, Comp.

2012-01-01

Technology touches people's lives virtually every second of the day. The work world is especially rich with changing technologies, new innovations, and continually revised processes for greater effectiveness and efficiency. One could easily say that a boiler is a boiler, or a carpet is a carpet, but the reality is that all components of all the…

A generalized transformation to convert an arbitrary perfect electric conductor into another arbitrary dielectric object

International Nuclear Information System (INIS)

Huang Lujun; Zhou Daming; Wang Jian; Li Guanhai; Li Zhifeng; Chen Xiaoshuang; Lu Wei

2011-01-01

A generalized transformation is proposed to design an illusion device. The device can reshape an arbitrarily shaped perfect electrical conductor (PEC) into another dielectric object with arbitrary geometry. Such a device can evolve into an ideal invisibility cloak with non-conformal boundaries if the virtual space is filled with air. Furthermore, the validity of our proposed transformation is confirmed by two specific devices. One is to convert a regular polygonal PEC cylinder into a circular dielectric cylinder. Another one is to reshape a circular PEC cylinder into a regular polygonal dielectric cylinder.

PRIVACYGRID: Supporting Anonymous Location Queries in Mobile Environments

Science.gov (United States)

2007-01-01

cid. 10: cidh ←− Horizontal neighbor cell of cid. 11: MNv = cid.MN + cidv.MN ; MNh = cid.MN + cidh.MN ; 12: SNv = cid.SN +cidv.SN ;SNh = cid.SN +cidh.SN...13: if (((MNv ≥ k) && (SNv ≥ l)) ‖ (( MNh ≥ k) && (SNh ≥ l))) then 14: if ((MNv ≥ k && MNh ≥ k && MNh > MNv) ‖ MNv < k) then 15: CheckCloakingBoxV...alidity(x, y, dx, dy) 16: return cid, cidh; 17: else 18: if ( MNh == MNv) then 19: if (SNh ≥ SNv) then 20: CheckCloakingBoxV alidity(x, y, dx, dy) 21

Interior design preferences of residents, families, and staff in two nursing homes.

Science.gov (United States)

Miller, D B; Goldman, L E; Woodman, S A

1985-01-01

The small number of respondents and the absence of specific demographic data concerning the three categories of respondents represented definite limitations. Further investigation in other long-term care facilities clearly is indicated. However, as a preliminary survey of preferences in nursing home interior design, several interesting findings have emerged: Patients, staff and families all emphasized patient safety and function over aesthetics. Yet, more residents than staff and families were concerned with appearance. Although experts advocate creating a home-like atmosphere in the nursing home, 50% or more of each group applied different criteria for specific design elements for private homes and for long-term care institutions. Design preferences for the three groups were similar, with an emphasis on modern furniture, painted walls, resilient tile rather than carpet, blinds, pastel and warm colors, and the use of paintings as accessories. Contrary to study assumptions, design features that promote patient individuality (e.g., patient artwork) received much greater emphasis from staff than from patients and families. Environmental change was considered an important aspect of interior design. Of the three constituencies, staff was most aware of periodic changes in decor and considered change as "very important" more often than did families or patients. As the nature of the nursing home patient population has changed--with residents presenting more disability and less rehabilitation potential and less likelihood of returning home--the ambiance of facilities has assumed even more importance. Clearly, the design preferences of residents who live in the facility are of paramount importance. However, it is also helpful to have an environment that is pleasing to family members who often experience difficulty in ongoing visitations, particularly to intellectually impaired relatives. Maintaining staff morale at a high level is a constant challenge in a long-term care

Polyelectrolyte brushes at the air/water interface

International Nuclear Information System (INIS)

Matsuoka, Hideki

2005-01-01

The nanostructure of amphiphilic diblock copolymer monolayer on water surface was investigated by in situ X-ray and neutron reflectivity. The diblock copolymers used have a long hydrophobic chain and a polyelectrolyte chain as a hydrophilic block. The monolayer was found not to have a simple double layer structure (hydrophobic layer / hydrophilic (carpet) layer) but to have a three layer structure consisting of hydrophobic layer, hydrophilic dense carpet layer, and polyelectrolyte brush layer when the polyelectrolyte block is long enough and the surface pressure (i.e. brush density) is high enough. The transition from carpet only to carpet/brush double layer structure in hydrophilic layer was observed as a function of polyelectrolyte chain length, the surface pressure. When the hydrophilic chain is a weak polyelectrolyte, the monolayer first expanded and then shrunk with increasing salt concentration in the subphase. For the strongly ionic polyelectrolyte, the monolayer structure was not affected by salt addition up to ∼0.2 M. These observations can be explained by a balance of the charged state of the brush chain, an electrostatic repulsion between brush chains and salt concentration in the brush layer

Illusion optics in chaotic light

International Nuclear Information System (INIS)

Zhang Suheng; Gan Shu; Xiong Jun; Zhang Xiangdong; Wang Kaige

2010-01-01

The time-reversal process provides the possibility to counteract the time evolution of a physical system. Recent research has shown that such a process can occur in the first-order field correlation of chaotic light and result in the spatial interference and phase-reversal diffraction in an unbalanced interferometer. Here we report experimental investigations on the invisibility cloak and illusion phenomena in chaotic light. In an unbalanced interferometer illuminated by thermal light, we have observed the cloak effect and the optical transformation of one object into another object. The experimental results can be understood by the phase-reversal diffraction, and they demonstrate the theoretical proposal of similar effects in complementary media.

Acoustic cloaking by a near-zero-index phononic crystal

KAUST Repository

Zheng, Li-Yang

2014-04-21

Zero-refractive-index materials may lead to promising applications in various fields. Here, we design and fabricate a near Zero-Refractive-Index (ZRI) material using a phononic crystal (PC) composed of a square array of densely packed square iron rods in air. The dispersion relation exhibits a nearly flat band across the Brillouin zone at the reduced frequency f  = 0.5443c/a, which is due to Fabry-Perot (FP) resonance. By using a retrieval method, we find that both the effective mass density and the reciprocal of the effective bulk modulus are close to zero at frequencies near the flat band. We also propose an equivalent tube network model to explain the mechanisms of the near ZRI effect. This FP-resonance-induced near ZRI material offers intriguing wave manipulation properties. We demonstrate both numerically and experimentally its ability to shield a scattering obstacle and guide acoustic waves through a bent structure.

Gradient index metamaterials realized by drilling hole arrays

International Nuclear Information System (INIS)

Mei Zhonglei; Cui Tiejun; Bai Jing

2010-01-01

Gradient index metamaterials have wide applications in the microwave and optical fields. Based on the quasi-static theory, such materials at the microwave band have been realized by drilling hole arrays on ordinary dielectric materials. As applications of the gradient index metamaterials, novel devices including a 45 0 dielectric wave-bending structure, a 16 0 wave-steering lens and a microwave focusing lens are designed and fabricated. Field mapping measurements validate the proposed gradient index metamaterials and the device designs. The method can be directly and easily extended to the design of cloaks, various lenses, beam shifters and beam-steering devices. It can also be applied in the optical band as long as quasi-static conditions are satisfied. The method and the devices may find applications in integrated circuit systems.

Metamaterials and wave control

CERN Document Server

Lheurette, Eric

2013-01-01

Since the concept was first proposed at the end of the 20th Century, metamaterials have been the subject of much research and discussion throughout the wave community. More than 10 years later, the number of related published articles is increasing significantly. Onthe one hand, this success can be attributed to dreams of new physical objects which are the consequences of the singular properties of metamaterials. Among them, we can consider the examples of perfect lensing and invisibility cloaking. On other hand,metamaterials also provide new tools for the design of well-known wave functions s

Ecology: Electrical Cable Bacteria Save Marine Life

DEFF Research Database (Denmark)

Nielsen, Lars Peter

2016-01-01

Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide.......Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide....

Multimode Interference: Identifying Channels and Ridges in Quantum Probability Distributions

OpenAIRE

O'Connell, Ross C.; Loinaz, Will

2004-01-01

The multimode interference technique is a simple way to study the interference patterns found in many quantum probability distributions. We demonstrate that this analysis not only explains the existence of so-called "quantum carpets," but can explain the spatial distribution of channels and ridges in the carpets. With an understanding of the factors that govern these channels and ridges we have a limited ability to produce a particular pattern of channels and ridges by carefully choosing the ...

Porosimetry and packing morphology of vertically-aligned carbon nanotube arrays via impedance spectroscopy.

Science.gov (United States)

Mutha, Heena K; Lu, Yuan; Stein, Itai; Cho, H Jeremy; Suss, Matthew; Laoui, Tahar; Thompson, Carl; Wardle, Brian; Wang, Evelyn

2016-12-13

Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes. In this work, we combined electrochemical impedance spectroscopy (EIS) with capacitance measurements and porous electrode theory to conduct in situ porosimetry of vertically-aligned carbon nanotubes (VA-CNTs) non-destructively. We utilized the EIS measurements with a pore size distribution model to quantify the average and dispersion of inter-CNT spacing (Γ), stochastically, in carpets that were mechanically densified from 1.7 × 1010 tubes/cm2 to 4.5 × 1011 tubes/cm2. Our analysis predicts that the inter-CNT spacing ranges from over 100 ± 50 nm in sparse carpets to sub 10 ± 5 nm in packed carpets. Our results suggest that waviness of CNTs leads to variations in the inter-CNT spacing, which can be significant in sparse carpets. This methodology can be used to predict the performance of many nanostructured devices, including supercapacitors, batteries, solar cells, and semiconductor electronics. Copyright 2016 IOP Publishing Ltd.

Electrical device fabrication from nanotube formations

Science.gov (United States)

Nicholas, Nolan Walker; Kittrell, W. Carter; Kim, Myung Jong; Schmidt, Howard K.

2013-03-12

A method for forming nanotube electrical devices, arrays of nanotube electrical devices, and device structures and arrays of device structures formed by the methods. Various methods of the present invention allow creation of semiconducting and/or conducting devices from readily grown SWNT carpets rather than requiring the preparation of a patterned growth channel and takes advantage of the self-controlling nature of these carpet heights to ensure a known and controlled channel length for reliable electronic properties as compared to the prior methods.

Anomalous behaviors during infiltration into heterogeneous porous media

Science.gov (United States)

Aarão Reis, F. D. A.; Bolster, D.; Voller, V. R.

2018-03-01

Flow and transport in heterogeneous porous media often exhibit anomalous behavior. A physical analog example is the uni-directional infiltration of a viscous liquid into a horizontal oriented Hele-Shaw cell containing through thickness flow obstacles; a system designed to mimic a gravel/sand medium with impervious inclusions. When there are no obstacles present or the obstacles form a multi-repeating pattern, the change of the length of infiltration F with time t tends to follow a Fickian like scaling, F ∼t1/2 . In the presence of obstacle fields laid out as Sierpinski carpet fractals, infiltration is anomalous, i.e., F ∼ tn, n ≠ 1/2. Here, we study infiltration into such Hele-Shaw cells. First we investigate infiltration into a square cell containing one fractal carpet and make the observation that it is possible to generate both sub (n 1/2) diffusive behaviors within identical heterogeneity configurations. We show that this can be explained in terms of a scaling analysis developed from results of random-walk simulations in fractal obstacles; a result indicating that the nature of the domain boundary controls the exponent n of the resulting anomalous transport. Further, we investigate infiltration into a rectangular cell containing several repeats of a given Sierpinski carpet. At very early times, before the liquid encounters any obstacles, the infiltration is Fickian. When the liquid encounters the first (smallest scale) obstacle the infiltration sharply transitions to sub-diffusive. Subsequently, around the time where the liquid has sampled all of the heterogeneity length scales in the system, there is a rapid transition back to Fickian behavior. An explanation for this second transition is obtained by developing a simplified infiltration model based on the definition of a representative averaged hydraulic conductivity.

Epidemiological survey of patients with a carpal tunnel syndrome referred to Sina Hospital in Hamedan during 2014-2016

Directory of Open Access Journals (Sweden)

Masoud Ghiasian

2017-11-01

Full Text Available Background: Carpal tunnel syndrome is a common mono-neuropathy with various causes. This study aimed at evaluating the epidemiology of patients with the carpal tunnel syndrome referred to Sina Hospital in Hamedan City, Iran. Materials and Methods: In this descriptive-cross sectional study, 300 patients (600 hands suffering from paresthesia, pain and weakness of the first to third finger were studied. Diagnosis and severity of the disease was evaluated according to history, examination and electro-diagnostic studies. Afterall the data were collected. Results: This study was conducted on 230 (76.7% females and 70 (23.3% males with the mean ages of 47.3±17.4 and 49.1±20.2 years, respectively (P=0.224. Sixteen of them were left-handed and the rest were right-handed. Also, 113 of the patients had risk factors such as diabetes with the prevalence of 18.1% and hypothyroidism with 6.4% as the most common ones. The most common occupations were carpet weaving and milking with prevalence rates of 19.4% and 13.3%, respectively. In electro-diagnostic findings, 57% of the patients had moderate involvement and 16.6% had severe involvement. The Phalen and Tinel test was positive in 32.2% of the patients and negative in 32.2% of the cases. There was a relationship between the severity of involvement and probability of a positive Phalen and Tinel test. Conclusion: Considering that 76% of the cases were women and among jobs, after housekeeping, carpet weaving and milking are the most common ones, paying more attention to these people and designing the proper work tools (especially carpet weaving and milking tools as well as training of the housewives are recommended to prevent this syndrome.

Transient thermal camouflage and heat signature control

Science.gov (United States)

Yang, Tian-Zhi; Su, Yishu; Xu, Weikai; Yang, Xiao-Dong

2016-09-01

Thermal metamaterials have been proposed to manipulate heat flux as a new way to cloak or camouflage objects in the infrared world. To date, however, thermal metamaterials only operate in the steady-state and exhibit detectable, transient heat signatures. In this letter, the theoretical basis for a thermal camouflaging technique with controlled transient diffusion is presented. This technique renders an object invisible in real time. More importantly, the thermal camouflaging device instantaneously generates a pre-designed heat signature and behaves as a perfect thermal illusion device. A metamaterial coating with homogeneous and isotropic thermal conductivity, density, and volumetric heat capacity was fabricated and very good camouflaging performance was achieved.

Realization of low-scattering metamaterial shell based on cylindrical wave expanding theory.

Science.gov (United States)

Wu, Xiaoyu; Hu, Chenggang; Wang, Min; Pu, Mingbo; Luo, Xiangang

2015-04-20

In this paper, we demonstrate the design of a low-scattering metamaterial shell with strong backward scattering reduction and a wide bandwidth at microwave frequencies. Low echo is achieved through cylindrical wave expanding theory, and such shell only contains one metamaterial layer with simultaneous low permittivity and permeability. Cut-wire structure is selected to realize the low electromagnetic (EM) parameters and low loss on the resonance brim region. The full-model simulations show good agreement with theoretical calculations, and illustrate that near -20dB reduction is achieved and the -10 dB bandwidth can reach up to 0.6 GHz. Compared with the cloak based on transformation electromagnetics, the design possesses advantage of simpler requirement of EM parameters and is much easier to be implemented when only backward scattering field is cared.

The Warm Plasma Composition in the Inner Magnetosphere during 2012-2015

Science.gov (United States)

Jahn, J. M.; Goldstein, J.; Reeves, G. D.; Fernandes, P. A.; Skoug, R. M.; Larsen, B.; Spence, H. E.

2017-12-01

Ionospheric heavy ions play an important role in the dynamics of Earth's magnetosphere. The greater mass and gyro radius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during geomagnetic storms. At sub-keV energies, multi-species ion populations in the inner magnetosphere form the warm plasma cloak, occupying the energy range between the plasmasphere and the ring current. Lastly, cold lighter ions from the mid-latitude ionosphere create the co-rotating plasmasphere whose outer regions can interact with the plasma cloak, plasma sheet, ring current, and outer electron belt. In this paper we present a statistical view of warm, cloak-like ion populations in the inner magnetosphere, contrasting in particular the warm plasma composition during quiet and active times. We study the relative abundances and absolute densities of warm plasma measured by the Van Allen Probes, whose two spacecraft cover the inner magnetosphere from plasmaspheric altitudes close to Earth to just inside geostationary orbit. We observe that warm (> 30 eV) oxygen is most abundant closer to the plasmasphere boundary whereas warm hydrogen dominates closer to geostationary orbit. Warm helium is usually a minor constituent, but shows a noticeable enhancement in the near-Earth dusk sector.

The influence of headform orientation and flooring systems on impact dynamics during simulated fall-related head impacts.

Science.gov (United States)

Wright, Alexander D; Laing, Andrew C

2012-10-01

Novel compliant flooring systems are a promising approach for reducing fall-related injuries in seniors, as they may provide up to 50% attenuation in peak force during simulated hip impacts while eliciting only minimal influences on balance. This study aimed to determine the protective capacity of novel compliant floors during simulated 'high severity' head impacts compared to common flooring systems. A headform was impacted onto a common Commercial-Carpet at 1.5, 2.5, and 3.5 m/s in front, back, and side orientations using a mechanical drop tower. Peak impact force applied to the headform (F(max)), peak linear acceleration of the headform (g(max)) and Head Injury Criterion (HIC) were determined. For the 3.5 m/s trials, backwards-oriented impacts were associated with the highest F(max) and HIC values (pfloors (Resilient Rubber, Residential-Loop Carpet, Berber Carpet) and six novel compliant floors at each impact velocity. ANOVAs indicated that flooring type was associated with all parameters at each impact velocity (pfloors (pfloors can substantially reduce the forces and accelerations applied to a headform compared to common floors including carpet and resilient rubber. In combination with reports of minimal balance impairments, these findings support the promise of novel compliant floors as a biomechanically effective strategy for reducing fall-related injuries including traumatic brain injuries and skull fractures. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Challenges of Recognition of the Psychiatric Aspects of Intimate ...

African Journals Online (AJOL)

hanumantp

Enugu, Enugu State, 1Department of Obstetrics and Gynecology, Faculty of Clinical Medicine, College of Health ... and cloaking of their emotional distress in somatic complaints. Also ..... Tyree A. Prevalence and stability of physical aggression.

A first generation dynamic ingress, redistribution and transport model of soil track-in: DIRT.

Science.gov (United States)

Johnson, D L

2008-12-01

This work introduces a spatially resolved quantitative model, based on conservation of mass and first order transfer kinetics, for following the transport and redistribution of outdoor soil to, and within, the indoor environment by track-in on footwear. Implementations of the DIRT model examined the influence of room size, rug area and location, shoe size, and mass transfer coefficients for smooth and carpeted floor surfaces using the ratio of mass loading on carpeted to smooth floor surfaces as a performance metric. Results showed that in the limit for large numbers of random steps the dual aspects of deposition to and track-off from the carpets govern this ratio. Using recently obtained experimental measurements, historic transport and distribution parameters, cleaning efficiencies for the different floor surfaces, and indoor dust deposition rates to provide model boundary conditions, DIRT predicts realistic floor surface loadings. The spatio-temporal variability in model predictions agrees with field observations and suggests that floor surface dust loadings are constantly in flux; steady state distributions are hardly, if ever, achieved.

Tuning the Color of Silicon Nanostructures

KAUST Repository

Cao, Linyou; Fan, Pengyu; Barnard, Edward S.; Brown, Ana M.; Brongersma, Mark L.

2010-01-01

and Si structures have already been engineered to enable light emission, optical cloaking, waveguiding, nonlinear optics, enhanced light absorption, and sensing. Here, we demonstrate that a wide spectrum of colors can be generated by harnessing the strong

The influence of flooring on environmental stressors: a study of three flooring materials in a hospital.

Science.gov (United States)

Harris, Debra D

2015-01-01

Three flooring materials, terrazzo, rubber, and carpet tile, in patient unit corridors were compared for absorption of sound, comfort, light reflectance, employee perceptions and preferences, and patient satisfaction. Environmental stressors, such as noise and ergonomic factors, effect healthcare workers and patients, contributing to increased fatigue, anxiety and stress, decreased productivity, and patient safety and satisfaction. A longitudinal comparative cohort study comparing three types of flooring assessed sound levels, healthcare worker responses, and patient Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) ratings over 42 weeks. A linear mixed model analysis was conducted to determine significant differences between the means for participant responses and objective sound meter data during all three phases of the study. A significant difference was found for sound levels between flooring type for equivalent continuous sound levels. Carpet tile performed better for sound attenuation by absorption, reducing sound levels 3.14 dBA. Preferences for flooring materials changed over the course of the study. The HCAHPS ratings aligned with the sound meter data showing that patients perceived the noise levels to be lower with carpet tiles, improving patient satisfaction ratings. Perceptions for healthcare staff and patients were aligned with the sound meter data. Carpet tile provides sound absorption that affects sound levels and influences occupant's perceptions of environmental factors that contribute to the quality of the indoor environment. Flooring that provides comfort underfoot, easy cleanability, and sound absorption influence healthcare worker job satisfaction and patient satisfaction with their patient experience. © The Author(s) 2015.

Mines and Underwater IEDs in U.S. Ports and Waterways: Context, Threats, Challenges, and Solutions

National Research Council Canada - National Science Library

Truver, Scott C

2008-01-01

.... Under the cloak of legal activity, groups that would do the United States harm can enter the U.S. homeland anywhere along more than 95,000 miles of coastlines and through some 360 ports from Maine to Guam...

A hybrid technique for private location-based queries with database protection

KAUST Repository

Ghinita, Gabriel; Kalnis, Panos; Kantarcioǧlu, Murâ t; Bertino, Elisa

2009-01-01

on finding good trade-offs between privacy and performance of user protection techniques, but disregarded the important issue of protecting the POI dataset D. For instance, location cloaking requires large-sized CRs, leading to excessive disclosure of POIs (O

Platelet mimicry

DEFF Research Database (Denmark)

Moghimi, Seyed Moein; Hunter, Alan Christy; Peer, Dan

2016-01-01

Here we critically examine whether coating of nanoparticles with platelet membranes can truly disguise them against recognition by elements of the innate immune system. We further assess whether the "cloaking technology" can sufficiently equip nanoparticles with platelet-mimicking functionalities...

Pyrolysis Model Development for a Multilayer Floor Covering

Directory of Open Access Journals (Sweden)

Mark B. McKinnon

2015-09-01

Full Text Available Comprehensive pyrolysis models that are integral to computational fire codes have improved significantly over the past decade as the demand for improved predictive capabilities has increased. High fidelity pyrolysis models may improve the design of engineered materials for better fire response, the design of the built environment, and may be used in forensic investigations of fire events. A major limitation to widespread use of comprehensive pyrolysis models is the large number of parameters required to fully define a material and the lack of effective methodologies for measurement of these parameters, especially for complex materials. The work presented here details a methodology used to characterize the pyrolysis of a low-pile carpet tile, an engineered composite material that is common in commercial and institutional occupancies. The studied material includes three distinct layers of varying composition and physical structure. The methodology utilized a comprehensive pyrolysis model (ThermaKin to conduct inverse analyses on data collected through several experimental techniques. Each layer of the composite was individually parameterized to identify its contribution to the overall response of the composite. The set of properties measured to define the carpet composite were validated against mass loss rate curves collected at conditions outside the range of calibration conditions to demonstrate the predictive capabilities of the model. The mean error between the predicted curve and the mean experimental mass loss rate curve was calculated as approximately 20% on average for heat fluxes ranging from 30 to 70 kW·m−2, which is within the mean experimental uncertainty.

Erythrocyte membrane modified janus polymeric motors for thrombus therapy

NARCIS (Netherlands)

Shao, Jingxin; Abdelghani, Mona; Shen, Guizhi; Cao, Shoupeng; Williams, David S.; van Hest, Jan C.M.

2018-01-01

We report the construction of erythrocyte membrane-cloaked Janus polymeric motors (EM-JPMs) which are propelled by near-infrared (NIR) laser irradiation and are successfully applied in thrombus ablation. Chitosan (a natural polysaccharide with positive charge, CHI) and heparin (glycosaminoglycan

Three-Dimensionally Isotropic Negative Refractive Index Materials from Block Copolymer Self-Assembled Chiral Gyroid Networks

KAUST Repository

Hur, Kahyun

2011-10-17

Metamaterials are engineered artificial materials that offer new functionalities such as super-resolution imaging and cloaking. Calculations of the photonic properties of three-dimensionally isotropic metamaterials with cubic double gyroid and alternating gyroid morphologies from block copolymer self-assembly are presented.

Metamaterials, from electromagnetic waves to water waves, bending waves and beyond

KAUST Repository

Dupont, G.

2015-08-04

We will review our recent work on metamaterials for different types of waves. Transposition of transform optics to water waves and bending waves on plates will be considered with potential applications of cloaking to water waves protection and anti-vibrating systems.

Bevalac Radiotherapy Facility

International Nuclear Information System (INIS)

Alonso, J.R.; Howard, J.; Criswell, T.

1979-03-01

Patient Treatment Room at the Bevalac is now in full operation. In the design of this facility, emphasis has been placed on creating an atmosphere appropriate to a clinical facility; the usual features of an irradiation cave have been hidden behind carpets, curtains and paint. Patient positioning is done with a Philips Ram-style couch, with additional fixtures to accommodate a patient in the seated or standing, as well as the supine, position. Dosimetry apparatus, collimators, ion chambers and the beam flattening system used to produce the highly uniform 20 cm diameter therapy field are described

Bevalac Radiotherapy Facility

Energy Technology Data Exchange (ETDEWEB)

Alonso, J.R.; Howard, J.; Criswell, T.

1979-03-01

Patient Treatment Room at the Bevalac is now in full operation. In the design of this facility, emphasis has been placed on creating an atmosphere appropriate to a clinical facility; the usual features of an irradiation cave have been hidden behind carpets, curtains and paint. Patient positioning is done with a Philips Ram-style couch, with additional fixtures to accommodate a patient in the seated or standing, as well as the supine, position. Dosimetry apparatus, collimators, ion chambers and the beam flattening system used to produce the highly uniform 20 cm diameter therapy field are described.

The biosphere rules.

Science.gov (United States)

Unruh, Gregory C

2008-02-01

Sustainability, defined by natural scientists as the capacity of healthy ecosystems to function indefinitely, has become a clarion call for business. Leading companies have taken high-profile steps toward achieving it: Wal-Mart, for example, with its efforts to reduce packaging waste, and Nike, which has removed toxic chemicals from its shoes. But, says Unruh, the director of Thunderbird's Lincoln Center for Ethics in Global Management, sustainability is more than an endless journey of incremental steps. It is a destination, for which the biosphere of planet Earth--refined through billions of years of trial and error--is a perfect model. Unruh distills some lessons from the biosphere into three rules: Use a parsimonious palette. Managers can rethink their sourcing strategies and dramatically simplify the number and types of materials their companies use in production, making recycling cost-effective. After the furniture manufacturer Herman Miller discovered that its leading desk chair had 200 components made from more than 800 chemical compounds, it designed an award-winning successor whose far more limited materials palette is 96% recyclable. Cycle up, virtuously. Manufacturers should design recovery value into their products at the outset. Shaw Industries, for example, recycles the nylon fiber from its worn-out carpet into brand-new carpet tile. Exploit the power of platforms. Platform design in industry tends to occur at the component level--but the materials in those components constitute a more fundamental platform. Patagonia, by recycling Capilene brand performance underwear, has achieved energy costs 76% below those for virgin sourcing. Biosphere rules can teach companies how to build ecologically friendly products that both reduce manufacturing costs and prove highly attractive to consumers. And managers need not wait for a green technological revolution to implement them.

Family and home characteristics correlate with mold in homes.

Science.gov (United States)

Reponen, Tiina; Levin, Linda; Zheng, Shu; Vesper, Stephen; Ryan, Patrick; Grinshpun, Sergey A; LeMasters, Grace

2013-07-01

Previously, we demonstrated that infants residing in homes with higher Environmental Relative Moldiness Index were at greater risk for developing asthma by age seven. The purpose of this analysis was to identify the family and home characteristics associated with higher moldiness index values in infants' homes at age one. Univariate linear regression of each characteristic determined that family factors associated with moldiness index were race and income. Home characteristics associated with the moldiness index values were: air conditioning, carpet, age of the home, season of home assessment, and house dust mite allergen. Parental history of asthma, use of dehumidifier, visible mold, dog and cat allergen levels were not associated with moldiness index. Results of multiple linear regression showed that older homes had 2.9 units higher moldiness index (95% confidence interval [CI]=0.4, 5.4), whereas homes with central air conditioning had 2.5 units lower moldiness index (95% CI=-4.7, -0.4). In addition, higher dust mite allergen levels and carpeting were positively and negatively associated with higher moldiness index, respectively. Because older homes and lack of air conditioning were also correlated with race and lower income, whereas carpeting was associated with newer homes, the multivariate analyses suggests that lower overall socioeconomic position is associated with higher moldiness index values. This may lead to increased asthma risk in homes inhabited by susceptible, vulnerable population subgroups. Further, age of the home was a surrogate of income, race and carpeting in our population; thus the use of these factors should carefully be evaluated in future studies. Copyright © 2013 Elsevier Inc. All rights reserved.

Dynamic behavior of semivolatile organic compounds in indoor air

Energy Technology Data Exchange (ETDEWEB)

Loy, Michael David Van [Univ. of California, Berkeley, CA (United States)

1998-12-09

Exposures to a wide range of air pollutants are often dominated by those occurring in buildings because of three factors: 1) most people spend a large fraction of their time indoors, 2) many pollutants have strong indoor sources, and 3) the dilution volume in buildings is generally several orders of magnitude smaller than that of an urban airshed. Semivolatile organic compounds (SVOCS) are emitted by numerous indoor sources, including tobacco combustion, cooking, carpets, paints, resins, and glues, so indoor gasphase concentrations of these compounds are likely to be elevated relative to ambient levels. The rates of uptake and release of reversibly sorbing SVOCS by indoor materials directly affect both peak concentrations and persistence of the pollutants indoors after source elimination. Thus, accurate predictions of SVOC dynamics in indoor air require an understanding of contaminant sorption on surface materials such as carpet and wallboard. The dynamic behaviors of gas-phase nicotine and phenanthrene were investigated in a 20 ms stainless steel chamber containing carpet and painted wallboard. Each compound was studied independently, first in the empty chamber, then with each sorbent individually, and finally with both sorbents in the chamber.

Countering urban segregation: Theoretical policy innovation from around the globe

NARCIS (Netherlands)

Smets, P.G.S.M.; Salman, A.J.

2008-01-01

New forms of urban segregation and exclusion have emerged in the contemporary globalised world. Processes of globalisation, especially those cloaked as free international trade and state withdrawal from economics, have led to increasing inequalities between and within cities. In response, the state,

Inverse problem in transformation optics

DEFF Research Database (Denmark)

Novitsky, Andrey

2011-01-01

The straightforward method of transformation optics implies that one starts from the coordinate transformation and determines the Jacobian matrix, the fields and material parameters of the cloak. However, the coordinate transformation appears as an optional function: it is not necessary to know it...

Effect of shear stress on electromagnetic behaviors in superconductor-ferromagnetic bilayer structure

Science.gov (United States)

Yong, Huadong; Zhao, Meng; Jing, Ze; Zhou, Youhe

2014-09-01

In this paper, the electromagnetic response and shielding behaviour of superconductor-ferromagnetic bilayer structure are studied. The magnetomechanical coupling in ferromagnetic materials is also considered. Based on the linear piezomagnetic coupling model and anti-plane shear deformation, the current density and magnetic field in superconducting strip are obtained firstly. The effect of shear stress on the magnetization of strip is discussed. Then, we consider the magnetic cloak for superconductor-ferromagnetic bilayer structure. The magnetic permeability of ferromagnetic material is obtained for perfect cloaking in uniform magnetic field with magnetomechanical coupling in ferromagnet. The simulation results show that the electromagnetic response in superconductors will change by applying the stress only to the ferromagnetic material. In addition, the performance of invisibility of structure for non-uniform field will be affected by mechanical stress. It may provide a method to achieve tunability of superconducting properties with mechanical loadings.

Nanophotonics

CERN Document Server

McGurn, Arthur

2018-01-01

This book gives a readable introduction to the important, rapidly developing, field of nanophotonics. It provides a quick understanding of the basic elements of the field, allowing students and newcomers to progress rapidly to the frontiers of their interests. Topics include: The basic mathematical techniques needed for the study of the materials of nanophotonic technology; photonic crystals and their applications as laser resonators, waveguides, and circuits of waveguides; the application of photonic crystals technology in the design of optical diodes and transistors; the basic properties needed for the design and understanding of new types of engineered materials known as metamaterials; and a consideration of how and why these engineered materials have been formulated in the lab, as well as their applications as negative refractive index materials, as perfect lens, as cloaking devices, and their effects on Cherenkov and other types of radiation. Additionally, the book introduces the new field of plasmonics ...

Controlling sound with acoustic metamaterials

DEFF Research Database (Denmark)

Cummer, Steven A. ; Christensen, Johan; Alù, Andrea

2016-01-01

Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales....... The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create......-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview...

Controlling the flow of light with silicon nanostructures

International Nuclear Information System (INIS)

Park, W

2010-01-01

Silicon is an important material for integrated photonics applications. High refractive index and transparency in the infrared region makes it an ideal platform to implement nanostructures for novel optical devices. We fabricated silicon photonic crystals and experimentally demonstrated negative refraction and self-collimation. We also used heterodyne near-field scanning optical microscope to directly visualize the anomalous wavefronts. When the periodicity is much smaller than wavelength, silicon photonic crystal can be described by the effective medium theory. By engineering effective refractive index with silicon nanorod size, we demonstrated an all-dielectric cloak structure which can hide objects in front of a highly reflecting plane. The work discussed in this review shows the powerful design flexibility and versatility of silicon nanostructures

Sex, Pregnancy, and Schooling: Obstacles to a Critical Teaching of the Body.

Science.gov (United States)

McDade, Laurie A.

1987-01-01

Teachers, in their interactions with students, prevent a critical teaching of the body because of the following problems: (1) their information is cloaked in protectionism; (2) conservative educational policies hinder them; and (3) the classroom is too limited to adequately address the question. (Author/BJV)

Ethico-epistemological implications of artificial intelligence for ...

African Journals Online (AJOL)

We argued for a re-direction of AI. research and suggested a humanization of Artificial Intelligence that cloaks technoscientific innovations with humanistic life jackets for man‟s preservation. The textual analysis method is adopted for this research. Key words: Ethics, Epistemology, Artificial Intelligence, Humanity.

Raising Butterflies from Your Own Garden.

Science.gov (United States)

Howley-Pfeifer, Patricia

2002-01-01

Describes how raising monarch, black swallowtail, and mourning cloak butterflies in a kindergarten class garden can provide opportunities for observation experiences. Includes detailed steps for instruction and describes stages of growth. Excerpts children's journal dictations to illustrate ways to support the discovery process. Describes related…

A Walk Down the Red Carpet: Students as Producers of Digital Video-Based Knowledge.

OpenAIRE

Ryan, Barry

2013-01-01

Disengaged and apathetic students are common in many undergraduate classrooms. Learning to these students is a passive process, typified by a consumer-like attitude. One approach to engage students, and enhance the learning experience, is to integrate active learning into the curriculum. The purpose of the pedagogical evaluative study described here was to investigate if student researched, designed and created digital video could act as a viable reusable peer learning resource. Although the ...

Surface analysis and mechanical behaviour mapping of vertically aligned CNT forest array through nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Koumoulos, Elias P.; Charitidis, C.A., E-mail: charitidis@chemeng.ntua.gr

2017-02-28

Highlights: • Structure and wall numbers are identified through TEM. • Static contact angle measurements revealed a super-hydrophobic behavior. • Hysteresis was observed (loading–unloading) due to the local stress distribution. • Hardness and modulus mapping for a grid of 70 μm{sup 2} is conducted. • Resistance is clearly divided in 2 regions (MWCNT and MWCNT – MWCNT) interface. - Abstract: Carbon nanotube (CNT) based architectures have increased the scientific interest owning to their exceptional performance rendering them promising candidates for advanced industrial applications in the nanotechnology field. Despite individual CNTs being considered as one of the most known strong materials, much less is known about other CNT forms, such as CNT arrays, in terms of their mechanical performance (integrity). In this work, thermal chemical vapor deposition (CVD) method is employed to produce vertically aligned multiwall (VA-MW) CNT carpets. Their structural properties were studied by means of scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Raman spectroscopy, while their hydrophobic behavior was investigated via contact angle measurements. The resistance to indentation deformation of VA-MWCNT carpets was investigated through nanoindentation technique. The synthesized VA-MWCNTs carpets consisted of well-aligned MWCNTs. Static contact angle measurements were performed with water and glycerol, revealing a rather super-hydrophobic behavior. The structural analysis, hydrophobic behavior and indentation response of VA-MWCNTs carpets synthesized via CVD method are clearly demonstrated. Additionally, cycle indentation load-depth curve was applied and hysteresis loops were observed in the indenter loading–unloading cycle due to the local stress distribution. Hardness (as resistance to applied load) and modulus mapping, at 200 nm of displacement for a grid of 70 μm{sup 2} is presented. Through trajection, the resistance is clearly divided in 2

Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity.

Directory of Open Access Journals (Sweden)

Montserrat Torres-Oliva

2018-01-01

Full Text Available Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells.

Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity

Science.gov (United States)

Torres-Oliva, Montserrat; Schneider, Julia; Wiegleb, Gordon

2018-01-01

Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb) regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells) and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells. PMID:29360820

Ozone-surface reactions in five homes: surface reaction probabilities, aldehyde yields, and trends.

Science.gov (United States)

Wang, H; Morrison, G

2010-06-01

Field experiments were conducted in five homes during three seasons (summer 2005, summer 2006 and winter 2007) to quantify ozone-initiated secondary aldehyde yields, surface reaction probabilities, and trends any temporal over a 1.5-year interval. Surfaces examined include living room carpets, bedroom carpets, kitchen floors, kitchen counters, and living room walls. Reaction probabilities for all surfaces for all seasons ranged from 9.4 x 10(-8) to 1.0 x 10(-4). There were no significant temporal trends in reaction probabilities for any surfaces from summer 2005 to summer 2006, nor over the entire 1.5-year period, indicating that it may take significantly longer than this period for surfaces to exhibit any 'ozone aging' or lowering of ozone-surface reactivity. However, all surfaces in three houses exhibited a significant decrease in reaction probabilities from summer 2006 to winter 2007. The total yield of aldehydes for the summer of 2005 were nearly identical to that for summer of 2006, but were significantly higher than for winter 2007. We also observed that older carpets were consistently less reactive than in newer carpets, but that countertops remained consistently reactive, probably because of occupant activities such as cooking and cleaning. Ozone reactions taking place at indoor surfaces significantly influence personal exposure to ozone and volatile reaction products. These field studies show that indoor surfaces only slowly lose their ability to react with ozone over several year time frames, and that this is probably because of a combination of large reservoirs of reactive coatings and periodic additions of reactive coatings in the form of cooking, cleaning, and skin-oil residues. When considering exposure to ozone and its reaction products and in the absence of dramatic changes in occupancy, activities or furnishings, indoor surface reactivity is expected to change very slowly.

Red carpet for CERN's 50th

CERN Multimedia

2004-01-01

Scientists, heads of state, and representatives from many countries came to CERN's Official 50th Anniversary Ceremony 19 October to celebrate the Organization's 50th anniversary, and to praise its contributions to human knowledge while also fostering cooperation between scientists and their countries, across Europe and beyond.

By Force or by Fraud: Optimizing U.S. Information Strategy With Deception

Science.gov (United States)

2016-06-01

WITH DECEPTION Ryan Q. Flaherty Major, United States Army B.S., Sacred Heart University, 2001 M.B.A., Sacred Heart University, 2004...to hide their religious agenda of establishing an Islamic Republic under the cloak of Lebanese nationalism.163 B. UNITY OF EFFORT State Unity of

Jamming of Quantum Emitters by Active Coated Nanoparticles

DEFF Research Database (Denmark)

Arslanagic, Samel; Ziolkowski, Richard W.

2013-01-01

to effectively cloak the emitters to a far-field observer is reported and explained through thorough near- and far-field investigations. This property offers an interesting route toward the jamming of quantum emitters/nanoantennas that might be of potential use, for instance, in biological fluorescence assays...

76 FR 12873 - Potassium Benzoate; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2011-03-09

...., textiles (clothing and diapers), carpets, swimming pools, and hard surface disinfection on walls, floors... Executive Order 13211, entitled Actions Concerning Regulations That Significantly Affect Energy Supply...

76 FR 8895 - Polymerized Fatty Acid Esters With Aminoalcohol Alkoxylates; Exemption From the Requirement of a...

Science.gov (United States)

2011-02-16

... diapers), carpets, swimming pools, and hard surface disinfection on walls, floors, tables). The proposed... Executive Order 13211, entitled Actions Concerning Regulations That Significantly Affect Energy Supply...

Structural study and fabrication of nano-pattern on ultra thin film of Ag grown by magnetron sputtering

International Nuclear Information System (INIS)

Banerjee, S.; Mukherjee, S.; Kundu, S.

2001-01-01

We present the structural study of ultra thin Ag films using grazing incidence x-ray reflectivity and the modification of these films with the tip of an atomic force microscope. Ag thin films are deposited using dc magnetron sputtering on a Si(001) substrate. Initially, the growth of the film is carpet like and above a certain thickness (∼42 A) the film structure changes to form mounds. This ultra thin film of Ag having carpet-like growth can be modified by the tip of an atomic force microscope, which occurs due to the porous nature of the film. A periodic pattern of nanometer dimensions has been fabricated on this film using the atomic force microscope tip. (author)

Nanostructure of Cationic Polymer Brush at the Air/Water Interface

Directory of Open Access Journals (Sweden)

Matsuoka Hideki

2013-08-01

Full Text Available Cationic amphiphilic diblock copolymers were synthesized by RAFT polymerization and the nanostructure of their monolayers was investigated by π-A isotherm and X-ray reflectivity. Carpet layer (dense hydrophilic block layer formation under the hydrophobic layer was confirmed and a “brush” layer was found beneath the carpet layer. However, the thickness of brush layer was much thinner than that of the fully-stretched chain length. The critical salt concentration was found to be 0.01 M NaCl, which is much lower than that of the previous strongly anionic brush. These differences were probably caused by the low effective charge on the brush chains due to the hydrophobic nature of the quarternized ammonium cation.

Build green and conventional materials off-gassing tests: A final report

Energy Technology Data Exchange (ETDEWEB)

Piersol, P.

1995-12-31

Build Green is a certification program that will identify and label building products with a known recycled content. The introduction of these recycled materials has raised the concern that they may emit more indoor pollutants than conventional materials. This study addresses that concern by analyzing Build Green and conventional materials to assess their potential for off-gassing. The study involved emission tests of 37 materials including carpets, carpet undercushions, structural lumber, foundation material, insulation, drywall, fiberboard, counter tops, and cabinetry. The results presented in this report include comparisons of Build Green and conventional materials in terms of emissions of volatile organic compounds and formaldehyde, the material loading ratio, and discussion of the specific sources of the emissions.

Hazardous Asteroids: Cloaking STEM Skills Training within an Attention-Grabbing Science/Math Course

Science.gov (United States)

Ryan, Eileen V.; Ryan, William H.

2015-11-01

A graduate-level course was designed and taught during the summer months from 2009 - 2015 in order to contribute to the training and professional development of K-12 teachers residing in the Southwest. The teachers were seeking Master’s degrees via the New Mexico Institute of Mining and Technology’s (NMT’s) Masters of Science Teaching (MST) program, and the course satisfied a science or math requirement. The MST program provides opportunities for in-service teachers to enhance their content backgrounds in science, mathematics, engineering, and technology (SMET). The ultimate goal is to assist teachers in gaining knowledge that has direct application in the classroom.The engaging topic area of near-Earth object (NEO) characterization studies was used to create a fun and exciting framework for mastering basic skills and concepts in physics and astronomy. The objective was to offer a class that had the appropriate science rigor (with an emphasis on mathematics) within a non-threatening format. The course, entitled “Hazardous Asteroids”, incorporates a basic planetary physics curriculum, with challenging laboratories that include a heavy emphasis on math and technology. Since the authors run a NASA-funded NEO research and follow-up program, also folded into the course is the use of the Magdalena Ridge Observatory’s 2.4-meter telescope so participants can take and reduce their own data on a near-Earth asteroid.In exit assessments, the participants have given the course excellent ratings for design and implementation, and the overall degree of satisfaction was high. This validates that a well-constructed (and rigorous) course can be effective in receptively reaching teachers in need of basic skills refreshment. Many of the teachers taking the course were employed in school districts serving at-risk or under-prepared students, and the course helped provide them with the confidence vital to developing new strategies for successful teaching.

Broadband invisibility by non-Euclidean cloaking.

Science.gov (United States)

Leonhardt, Ulf; Tyc, Tomás

2009-01-02

Invisibility and negative refraction are both applications of transformation optics where the material of a device performs a coordinate transformation for electromagnetic fields. The device creates the illusion that light propagates through empty flat space, whereas in physical space, light is bent around a hidden interior or seems to run backward in space or time. All of the previous proposals for invisibility require materials with extreme properties. Here we show that transformation optics of a curved, non-Euclidean space (such as the surface of a virtual sphere) relax these requirements and can lead to invisibility in a broad band of the spectrum.

Ventilating Air-Conditioner

Science.gov (United States)

Dinh, Khanh

1994-01-01

Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

78 FR 32245 - Notice of Receipt of Pesticide Products; Registration Applications To Register New Uses

Science.gov (United States)

2013-05-29

... Road, Pasadena, TX 77507-1041. Active ingredient: Novaluron. Product Type: Insecticide; Insect Growth... furniture, animal quarters, carpets, kennels, and poultry houses. Contact: Jennifer Gaines, (703) 305-5967...

77 FR 20721 - 2-Ethyl-1-hexanol; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2012-04-06

...-occupational, non-dietary exposure (e.g., textiles (clothing and diapers), carpets, swimming pools, and hard... Executive Order 13211, entitled ``Actions Concerning Regulations That Significantly Affect Energy Supply...

76 FR 6347 - (S,S)-Ethylenediamine Disuccinic Acid Trisodium Salt; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2011-02-04

...., textiles (clothing and diapers), carpets, swimming pools, and hard surface disinfection on walls, floors..., entitled Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use (66...

Combined use of alkane-degrading and plant growth-promoting bacteria enhanced phytoremediation of diesel contaminated soil.

Science.gov (United States)

Tara, Nain; Afzal, Muhammad; Ansari, Tariq M; Tahseen, Razia; Iqbal, Samina; Khan, Qaiser M

2014-01-01

Inoculation of plants with pollutant-degrading and plant growth-promoting microorganisms is a simple strategy to enhance phytoremediation activity. The objective of this study was to determine the effect of inoculation of different bacterial strains, possessing alkane-degradation and 1-amino-cyclopropane-1 -carboxylic acid (ACC) deaminase activity, on plant growth and phytoremediation activity. Carpet grass (Axonopus affinis) was planted in soil spiked with diesel (1% w/w) for 90 days and inoculated with different bacterial strains, Pseudomonas sp. ITRH25, Pantoea sp. BTRH79 and Burkholderia sp. PsJN, individually and in combination. Generally, bacterial application increased total numbers of culturable hydrocarbon-degrading bacteria in the rhizosphere ofcarpet grass, plant biomass production, hydrocarbon degradation and reduced genotoxicity. Bacterial strains possessing different beneficial traits affect plant growth and phytoremediation activity in different ways. Maximum bacterial population, plant biomass production and hydrocarbon degradation were achieved when carpet grass was inoculated with a consortium of three strains. Enhanced plant biomass production and hydrocarbon degradation were associated with increased numbers of culturable hydrocarbon-degrading bacteria in the rhizosphere of carpet grass. The present study revealed that the combined use of different bacterial strains, exhibiting different beneficial traits, is a highly effective strategy to improve plant growth and phytoremediation activity.

Polarizing Beam Splitter: A New Approach Based on Transformation Optics

Science.gov (United States)

Mueller, Jonhatan; Wegener, Martin

Standard optical elements (e.g. lenses, prisms) are mostly designed of piecewise homogeneous and isotropic dielectrics. However, in theory one has far more possibilities to influence electromagnetic waves, namely all the components of the permittivity and permeability tensors. In the past few years, on the one hand, new micro fabrication methods allowed for new freedom in controlling of the optical parameters using so called artificial metamaterials. On the other hand, the theory of transformation optics has given a somewhat intuitive approach for the design of such structures. The most popular feature of this kind is certainly optical cloaking (i.e. [1,2]). However, the full capabilities of other transformation optical devices are far from being fully explored. In my work, I focused on pure dielectric structures in a non-resonant and therefore non-lossy regime. Although the relative permittivity one can achieve this way is limited by the available natural dielectrics, a broad spectrum of features can be realized.

Field approach in the transformation optics concept

DEFF Research Database (Denmark)

Novitsky, Andrey; Zhukovsky, Sergei; Barkovsky, L. M.

2012-01-01

distribution (e.g., Gaussian and sinusoidal) is studied to validate the effectiveness of the field-based formulation. As for the boundary conditions for the cloaked region the absence of the normal component of the Poynting vector is justified. In the frames of the field-based approach the physical reasons...

The EMC Informationist Chair: 2009 A Year in Review

Science.gov (United States)

2010-01-31

the right level or at the right volume: Is the information necessary or nice to have? Is it value added? Current political ‘ cloak & dagger ’ (an...their efforts to systematically attack these challenges and continue to work within our own government channels to simplify our processes to reduce

A Simple Derivation of Time Dilation and Length Contraction in Special Relativity

Science.gov (United States)

Behroozi, Fred

2014-01-01

Undergraduate physics majors typically begin their study of modern physics with special relativity. It is here that physics students first encounter the counterintuitive concepts of time dilation and length contraction. Unfortunately, the derivations of these results are often cloaked in several layers of analysis that render them rather…

77 FR 26004 - Product Cancellation Order for Certain Pesticide Registrations

Science.gov (United States)

2012-05-02

.... 010807-00110 Aqua-Kill Resmethrin. Insecticide. 028293-00160 Unicorn House and Tetramethrin, Carpet Spray..., LLC, 21 Hubble, Irvine, CA 92618. 86068 Texcan Investments & Marketing Company, Inc., Agent: Pyxis...

Microwave metamaterials—from passive to digital and programmable controls of electromagnetic waves

Science.gov (United States)

Cui, Tie Jun

2017-08-01

Since 2004, my group at Southeast University has been carrying out research into microwave metamaterials, which are classified into three catagories: metamaterials based on the effective medium model, plasmonic metamaterials for spoof surface plasmon polaritons (SPPs), and coding and programmable metamaterials. For effective-medium metamaterials, we have developed a general theory to accurately describe effective permittivity and permeability in semi-analytical forms, from which we have designed and realized a three dimensional (3D) wideband ground-plane invisibility cloak, a free-space electrostatic invisibility cloak, an electromagnetic black hole, optical/radar illusions, and radially anisotropic zero-index metamaterial for omni-directional radiation and a nearly perfect power combination of source array, etc. We have also considered the engineering applications of microwave metamaterials, such as a broadband and low-loss 3D transformation-optics lens for wide-angle scanning, a 3D planar gradient-index lens for high-gain radiations, and a random metasurface for reducing radar cross sections. In the area of plasmonic metamaterials, we proposed an ultrathin, narrow, and flexible corrugated metallic strip to guide SPPs with a small bending loss and radiation loss, from which we designed and realized a series of SPP passive devices (e.g. power divider, coupler, filter, and resonator) and active devices (e.g. amplifier and duplexer). We also showed a significant feature of the ultrathin SPP waveguide in overcoming the challenge of signal integrity in traditional integrated circuits, which will help build a high-performance SPP wireless communication system. In the area of coding and programmable metamaterials, we proposed a new measure to describe a metamaterial from the viewpoint of information theory. We have illustrated theoretically and experimentally that coding metamaterials composed of digital units can be controlled by coding sequences, leading to different

40 CFR 63.4281 - Am I subject to this subpart?

Science.gov (United States)

2010-07-01

..., carpets, high-performance industrial fabrics, luggage, military fabrics, outer wear, sheets, towels, and... tire manufacturing). This would include any web coating line that applies coatings to both tire cord...

78 FR 59265 - FD&C Yellow No. 5; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2013-09-26

... (clothing and diapers), carpets, swimming pools, and hard surface disinfection on walls, floors, tables... Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355, May 22...

Strong Selective Adsorption of Polymers.

Science.gov (United States)

Ge, Ting; Rubinstein, Michael

2015-06-09

A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker polymers strongly overlap. We anticipate the formation of a self-similar carpet and with increasing l / d a two-layer structure with a brush of loops covered by a self-similar carpet. As l / d exceeds the

The bleaching syndrome: manifestation of a post-colonial pathology ...

African Journals Online (AJOL)

The post-colonial root of African problems is directly related to skin color. Under the cloak of personal preference, light skin among African women has replaced dark skin as the native ideal. The aftermath is manifestation of the Bleaching Syndrome. Social Work professionals have overlooked the Bleaching Syndrome as ...

Extreme non-linear elasticity and transformation optics

DEFF Research Database (Denmark)

Gersborg, Allan Roulund; Sigmund, Ole

2010-01-01

realizations correspond to minimizers of elastic energy potentials for extreme values of the mechanical Poisson's ratio ν . For TE (Hz) polarized light an incompressible transformation ν = 1/2 is ideal and for TM (E z) polarized light one should use a compressible transformation with negative Poissons's ratio......Transformation optics is a powerful concept for designing novel optical components such as high transmission waveguides and cloaking devices. The selection of specific transformations is a non-unique problem. Here we reveal that transformations which allow for all dielectric and broadband optical...... ν = -1. For the TM polarization the mechanical analogy corresponds to a modified Liao functional known from the transformation optics literature. Finally, the analogy between ideal transformations and solid mechanical material models automates and broadens the concept of transformation optics...

76 FR 7703 - 1,4-Benzenedicarboxylic Acid, Dimethyl Ester, Polymer With 1,4-Butanediol, Adipic Acid, and...

Science.gov (United States)

2011-02-11

...., textiles (clothing and diapers), carpets, swimming pools, and hard surface disinfection on walls, floors... Regulations That Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22, 2001) or...

75 FR 34045 - Sodium 1,4-Dialkyl Sulfosuccinates; Exemption from the Requirement of a Tolerance

Science.gov (United States)

2010-06-16

..., non-dietary exposure (e.g., textiles (clothing and diapers), carpets, swimming pools, and hard surface... Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22...

75 FR 50891 - N-alkyl (C8-C18) Primary Amines and Acetate Salts; Exemption from the Requirement of a Tolerance

Science.gov (United States)

2010-08-18

...-dietary exposure (e.g., textiles (clothing and diapers), carpets, swimming pools, and hard surface... Regulations That Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22, 2001) or...

Robot Navigation Control Based on Monocular Images: An Image Processing Algorithm for Obstacle Avoidance Decisions

Directory of Open Access Journals (Sweden)

William Benn

2012-01-01

Full Text Available This paper covers the use of monocular vision to control autonomous navigation for a robot in a dynamically changing environment. The solution focused on using colour segmentation against a selected floor plane to distinctly separate obstacles from traversable space: this is then supplemented with canny edge detection to separate similarly coloured boundaries to the floor plane. The resulting binary map (where white identifies an obstacle-free area and black identifies an obstacle could then be processed by fuzzy logic or neural networks to control the robot’s next movements. Findings show that the algorithm performed strongly on solid coloured carpets, wooden, and concrete floors but had difficulty in separating colours in multicoloured floor types such as patterned carpets.

Metamaterial devices for molding the flow of diffuse light (Conference Presentation)

Science.gov (United States)

Wegener, Martin

2016-09-01

Much of optics in the ballistic regime is about designing devices to mold the flow of light. This task is accomplished via specific spatial distributions of the refractive index or the refractive-index tensor. For light propagating in turbid media, a corresponding design approach has not been applied previously. Here, we review our corresponding recent work in which we design spatial distributions of the light diffusivity or the light-diffusivity tensor to accomplish specific tasks. As an application, we realize cloaking of metal contacts on large-area OLEDs, eliminating the contacts' shadows, thereby homogenizing the diffuse light emission. In more detail, metal contacts on large-area organic light-emitting diodes (OLEDs) are mandatory electrically, but they cast optical shadows, leading to unwanted spatially inhomogeneous diffuse light emission. We show that the contacts can be made invisible either by (i) laminate metamaterials designed by coordinate transformations of the diffusion equation or by (ii) triangular-shaped regions with piecewise constant diffusivity, hence constant concentration of scattering centers. These structures are post-optimized in regard to light throughput by Monte-Carlo ray-tracing simulations and successfully validated by model experiments.

Pilot Implementation of a Field Study Design to Evaluate the Impact of Source Control Measures on Indoor Air Quality in High Performance Homes

Energy Technology Data Exchange (ETDEWEB)

Widder, Sarah H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chamness, Michele A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Petersen, Joseph M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Maddalena, Randy L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Destaillats, Hugo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Russell, M. L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-10-01

To improve the indoor air quality in new, high performance homes, a variety of standards and rating programs have been introduced to identify building materials that are designed to have lower emission rates of key contaminants of concern and a number of building materials are being introduced that are certified to these standards. For example, the U.S. Department of Energy (DOE) Zero Energy Ready Home program requires certification under the U.S. Environmental Protection Agency (EPA) Indoor airPLUS (IaP) label, which requires the use of PS1 or PS2 certified plywood and OSB; low-formaldehyde emitting wood products; low- or no-VOC paints and coatings as certified by Green Seal Standard GS-11, GreenGuard, SCS Indoor Advantage Gold Standard, MPI Green Performance Standard, or another third party rating program; and Green Label-certified carpet and carpet cushions. However, little is known regarding the efficacy of the IAP requirements in measurably reducing contaminant exposures in homes. The goal of this project is to develop a robust experimental approach and collect preliminary data to support the evaluation of indoor air quality (IAQ) measures linked to IAP-approved low-emitting materials and finishes in new residential homes. To this end, the research team of Pacific Northwest National Laboratory (PNNL) and Lawrence Berkeley National Laboratory (LBNL) developed a detailed experimental plan to measure IAQ constituents and other parameters, over time, in new homes constructed with materials compliant with IAP’s low-emitting material and ventilation requirements (i.e., section 6.1, 6.2, 6.3, and 7.2) and similar homes constructed to the state building code with conventional materials. The IAQ in IAP and conventional homes of similar age, location, and construction style is quantified as the differences in the speciated VOC and aldehyde concentrations, normalized to dilution rates. The experimental plan consists of methods to evaluate the difference between low

Plaadid / Tui Hirv

Index Scriptorium Estoniae

Hirv, Tui, 1984-

2007-01-01

Uutest heliplaatidest Andrea Bocelli "Vivere. The Best Of", Britney Spears "Blackout", John Fogerty "Revival", Bat For Lashes "Fur And Gold", Jimmy Eat World "Chase This Light", Duran Duran "Red Carpet Massacre"

77 FR 53144 - Nitric Acid; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2012-08-31

..., non-dietary exposure (e.g., textiles (clothing and diapers), carpets, swimming pools, and hard surface... Regulations That Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22, 2001) or...

75 FR 9877 - Notice of Petitions by Firms for Determination of Eligibility To Apply for Trade Adjustment...

Science.gov (United States)

2010-03-04

... countertops, ceramic Lee's Summit, MO tile floors and walls. Carpet, vinyl and 64064. wood. R.E. Hansen... primary products, filter presses, tube filters and pressure leaf filters. Colorado Case, Inc 1713 E...

76 FR 25236 - Carbon Dioxide; Exemption From the Requirement of a Tolerance

Science.gov (United States)

2011-05-04

... exposure (e.g., textiles (clothing and diapers), carpets, swimming pools, and hard surface disinfection on... Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22, 2001) or Executive Order 13045...

Characterization of the protective capacity of flooring systems using force-deflection profiling.

Science.gov (United States)

Glinka, Michal N; Karakolis, Thomas; Callaghan, Jack P; Laing, Andrew C

2013-01-01

'Safety floors' aim to decrease the risk of fall-related injuries by absorbing impact energy during falls. Ironically, excessive floor deflection during walking or standing may increase fall risk. In this study we used a materials testing system to characterize the ability of a range of floors to absorb energy during simulated head and hip impacts while resisting deflection during simulated single-leg stance. We found that energy absorption for all safety floors (mean (SD)=14.8 (4.9)J) and bedside mats (25.1 (9.3)J) was 3.2- to 5.4-fold greater than the control condition (commercial carpet). While footfall deflections were not significantly different between safety floors (1.8 (0.7)mm) and the control carpet (3.7 (0.6)mm), they were significantly higher for two bedside mats. Finally, all of the safety floors, and two bedside mats, displayed 3-10 times the energy-absorption-to-deflection ratios observed for the baseline carpet. Overall, these results suggest that the safety floors we tested effectively addressed two competing demands required to reduce fall-related injury risk; namely the ability to absorb substantial impact energy without increasing footfall deflections. This study contributes to the literature suggesting that safety floors are a promising intervention for reducing fall-related injury risk in older adults. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Evaluation of the concentration of allergens from mites in fur and households dust of dogs with atopic dermatitis

Directory of Open Access Journals (Sweden)

Dévaki L. de Assunção

Full Text Available ABSTRACT: This study evaluated the concentration of Der p 1, Der f 1 and Blo t 5 in the fur and households of 20 dogs with atopic dermatitis (AD and 20 healthy dogs. The diagnosis of AD was clinical based on Favrot’s criteria. Dust samples were collected with a domestic vacuum cleaner. For each site, 1m2 was vacuumed for 2 min. The samples were collected in separate filters, transferred into plastic containers, sealed and kept frozen until ELISA analysis. In the fur of atopic dogs the average concentration of Der p 1 was 0.25μg/g compared to 0.03μg/g in healthy dogs. In households with atopic dogs the highest concentrations of Der p 1 were found in carpets (2.18μg/g, followed by couches (1.53μg/g, beds (1.14μg/g, dogs’ bed linen (0.64μg/g and floors (0.14μg/g. The concentrations of Der p 1 on carpets, couches and beds were significantly higher than in atopic dogs’ fur (p0.05. The concentrations of Der p 1, Der f 1 and Blo t 5 were equivalent in atopic and non-atopic dog’s households. Among the allergens studied, Der p 1 was the most commonly found, predominantly in carpets and couches.

Hydraulic evaluation of the Crest Wing wave energy converter

Energy Technology Data Exchange (ETDEWEB)

Kofoed, J.P.; Antonishen, M.

2008-09-15

The Crest Wing Wave Energy Converter is currently being developed by Henning Pilgaard, of WaveEnergyFyn, Denmark. It is meant to act like a carpet on the water, conforming to the shape of each wave and using that movement to generate power. The thought of making a WEC that acts like a carpet on top of the waves is not new; ongoing or past projects such as the Pelamis and Cockerel Raft were designed with this thought in mind. The real difference with the Crest Wing is that it has skirt drafts, that extend down into the water and create suction; this increases the effective mass of the WEC while minimizing the material use. Special attention was given to the design of the first and last floaters as they are meant to act as a smooth transition between wave and machine. Their purpose is to make sure that no air gets under the two middle floaters so that suction is not broken and the device continues to function well. In summary the Crest Wing functions and is able to produce power with a good overall efficiency. The configuration with relative reference PTO (Power Take Off) is superior. It has not been proven that the idea of mounting skirts on the floaters is leading to a better performance. Thus, the study leads to the conclusion that the idea of making a simple hinged raft type device is good, and it is likely that the construction cost for a device of this type can be kept down. However, the study also leaves the chance that some limited draft of skirts in combination with inlet/outlet devices, could prove beneficial. In case of further testing on this device, an effort should be made to design and construct a more easily and accurately controlled PTO model in the test setup. This could greatly improve the quality of the output of such tests. (ln)

Russia's Uncertain Transition: Challenges for U.S. Policy. Fifth Edition. Teacher Resource Book [and Student Text]. Public Policy Debate in the Classroom. Choices for the 21st Century.

Science.gov (United States)

Fox, Sarah Cleveland

Since the end of the Cold War, and more recently since September 11, 2001, relations between the United States and Russia have reached new levels of cooperation and accommodation. At the same time, many important developments in Russia remain cloaked by government intrigue or obscured by the complexity of Russia's political and cultural past. This…

Does the removal of mite-infested brood facilitate grooming?

Science.gov (United States)

The relationship between the removal of mite-infested brood and mite drop was compared using Russian (RHB, n = 9) and Italian (IHB, n = 9) honey bee colonies. A cloake board was used to isolate test brood frame on the top hive body and the metal sheet served as a varroa trap. Inoculum mites were col...

“I Am the Wolf: Queering ‘Little Red Riding Hood’ and ‘Snow White and Rose Red’ in the Television Show Once Upon a Time”

Directory of Open Access Journals (Sweden)

Brittany Warman

2016-06-01

Full Text Available In season one, episode 15 of the television show Once Upon a Time, viewers are given a glimpse into the history of Ruby/Red, the series’ version of Red Riding Hood. The episode reveals that, contrary to most oral and written versions of the ATU 333 tale, Red herself is the wolf: a werewolf who must wear an enchanted red cloak in order to keep from turning into a monster. The episode also features the beginnings of the close friendship between Red and Snow White. The sisterly bond that quickly forms between the two women, combined with the striking images of their respective red and white cloaks, easily calls to mind a less familiar fairy tale not explicitly referenced in the series: “Snow White and Rose Red” (ATU 426. Taking queer readings of this text as starting points, I argue that this allusion complicates the bond between the two women, opening up space for a compelling reading of Red’s werewolf nature as a coded depiction of her then latent but later confirmed bisexuality.

The Baksan experiment on thunderstorm CR variations: history, results, and prospects

International Nuclear Information System (INIS)

Khaerdinov, N.S.; Lidvansky, A.S.

2016-01-01

Variations of cosmic rays in thunderstorm atmosphere, as measured at the Baksan Neutrino Observatory with the Carpet air shower array, are discussed. Their underlying mechanisms and accompanying phenomena are also considered. The observed effects in cosmic rays include regular variations with the near-ground electric field of the soft (electrons, positrons and gamma-rays) and hard (muons) components of secondary cosmic rays and sporadic changes in intensity of both these components (bright events). Associated phenomena occurring simultaneously with bright events in cosmic rays include geomagnetic pulsations (observed by high-sensitivity magnetic variation station deep underground) and large-scale atmospheric high-altitude discharge of a new type (observed by a video camera placed at a distance of 75 km from the Carpet array). Implications of all these results and prospects for further studies are discussed. (author)

$sup 155$Eu, $sup 144$Ce, $sup 125$Sb, $sup 106$Ru, $sup 95$Zr, $sup 54$Mn, and $sup 7$Be in the reindeer lichen Cladonia alpestris: deposition, retention and internal distribution, 1961--1970

Energy Technology Data Exchange (ETDEWEB)

Mattsson, L J.S.

1972-09-01

The retention and distribution of the fallout radionuclides , /sup 106/ Ru, /sup 95/Zr, and /sup 54/Mn and the naturally occurring radionuclide /sup 7/Be were studied in undisturbed natural carpets of the lichen Cladonia alpesiris, a major component of the diet of reindeer in the Lake Rogen district in central Sweden during the period 1961 to 1970. The contents of the artificially produced radionuclides in the lichen-carpet reached their maxima in 1963 to 1966 and all showed high retention values. During the seven-year period of 1962 to 1968 the average absorbed dose in the gut of a reindeer was calculated to be about 3 rad due to the passage of the food alone. The dominating contributions (about 40%) came from /sup 144/Ce. (CH)